IgG4 plasma cells in inflammatory myofibroblastic tumor: inflammatory marker or pathogenic link?

Treatment and outcomes in pediatric inflammatory myofibroblastic tumors - A systematic review of published studies

Inflammatory myofibroblastic tumor (IMT) is a soft tissue neoplasm which can be locally invasive, recur, or in rare cases metastasize. Often originating from the abdomen or thorax, IMT most commonly affects children and young adults. Due to its rarity comprehensive reports detailing clinical management and outcome(s) are sparse and often based on limited index case numbers. This study systematically analyzes outcome metrics of pediatric IMT and identifies risk factors for mortality. Medline/Embase databases were searched in accordance with PRISMA guidelines. Final analysis included 57 studies with 673 IMT patients (355 males, 53 %). Individual patient data was available for 405 cases with a median follow-up period of 36 months. Tumor sites included abdomen/pelvis (n = 233, 58 %), thorax (n = 125, 31 %), head/neck (n = 34, 8 %), and extremities (n = 13, 3 %). Surgical tumor resection was the mainstay of treatment, while only 20 patients (5 %) were treated non-operatively. Recurrence(s) were reported in 80 patients (20 %) with 34 (12 %) requiring reoperation. Positive tumor margins were a significant risk factor for tumor recurrence (p < 0.0001). Chemo/radiotherapy was reported in 98 patients (25 %). Most patients (94 %) survived; 81 % (n = 237) with no evidence of recurrent disease, 14 % (n = 41) were alive with disease, and 25 (6 %) died of disease. Positive margins at primary operation, and metastatic disease were associated with mortality (p < 0.0001 for both). IMT is a rare tumor with favorable outcome for the majority of patients. Whilst most patients will present with benign tumors, complete surgical resection (R0) is crucial, as positive surgical margins are a significant risk factor for tumor recurrence and mortality.

Differential diagnosis of IgG4-positive plasma cells in the lung

The recognition of immunoglobulin G4-related disease (IgG4-RD) as an entity in the pancreaticobiliary tract was followed by a slew of papers describing inflammation and fibrosis containing IgG4-positive plasma cells in a variety of sites including the respiratory tract, leading to the hypothesis that these abnormalities were attributable to IgG4-RD. Predictably, pathologists began to see requests from clinicians to perform IgG4 immunohistochemistry in lung biopsies "to rule out IgG4-RD". Several years later, the notion that IgG4-RD would prove to be the underlying cause of a wide array of fibroinflammatory lesions in the lung has not panned out as promised. To the contrary, it has become clear that IgG4-positive plasma cells are not specific for IgG4-RD, and that large numbers of IgG4-positive plasma cells can be encountered in other well-defined entities, including inflammatory myofibroblastic tumor and nodular lymphoid hyperplasia, as well as in lymphoplasmacytic infiltrates in other entities, including connective tissue disease and idiopathic forms of interstitial lung disease. It has also become clear that raised serum IgG4 levels can occur in settings other than IgG4-RD. These observations suggest that true IgG4-RD of the lung is far less common than previously surmised. Pathologists must familiarize themselves with mimics of IgG4-RD in the lung and exercise caution before attributing lymphoplasmacytic infiltrates in the lung to IgG4-RD.

Uterine inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is recognized as a true neoplasm of unknown etiology, but its pathogenesis is related to abnormalities in the ALK gene. This is an uncommon tumor with a wide anatomic distribution and often constitutes a challenging diagnosis owing to its histological similarities with other tumors. Uterine IMTs are rare and their detailed characteristics should be described based on case reports and small case series. Thus, we performed a comprehensive review of the literature showing that uterine IMTs show a wide range of age at diagnosis (median, 39 years), and a symptomatology similar to that of common leiomyomas, only rarely presenting with inflammatory manifestations. IMTs represent 0.1% of "leiomyomas," an estimate that increases to 10% for pregnant women and to 14% for the smooth muscle tumors of uncertain malignant potential (STUMP) category of tumors, implying that tumors excised during pregnancy, STUMPs, and leiomyosarcomas should be systematically screened with ALK immunohistochemistry, as this is a targetable abnormality. Most reported cases are ALK-positive; the fusion partners vary, but in pregnancy-associated tumors, TIMP3 prevails. Almost 25% of the patients will show an aggressive course, and this is associated with older age, non-pregnancy-associated tumors, larger tumors, infiltrative tumor border, absence of abundant inflammation, atypia, important mitotic activity, and necrosis.

Inflammatory Myofibroblastic Tumor of the Hilar Bile Duct: A Case Report and Literature Review

Background

Inflammatory myofibroblastic tumor (IMT) is a very rare tumor and occurs seldom in the biliary tract. IMT can occur in any part of the body and in people of any age; however, it most commonly occurs in children or adolescents. Its etiology and pathogenesis are currently unknown. The clinical manifestations of a hilar inflammatory myofibroblastic tumor are atypical, and the imaging examination is nonspecific. The diagnosis is mainly based on histopathology and immunohistochemistry findings, and surgical resection is the preferred treatment method.

Case Description

Herein, we report a rare case of hilar bile duct IMT and review the related literature. Our patient was a 54-year-old woman presenting with a 1-day history of upper abdominal pain as the main clinical symptom. She was misdiagnosed as having cholangiocarcinoma before the surgery. She underwent surgery and was ultimately diagnosed with IMT based on histopathology and immunohistochemistry findings. On 1-year follow-up, no tumor recurrence or related complications were noted.

Conclusions

We hope this case report helps clinicians gain a deeper understanding of biliary IMT of the hilum.

Locally Advanced Inflammatory Myofibroblastic Tumor Treated With Targeted Therapy: A Case Report and Literature Review

Inflammatory myofibroblastic tumors (IMTs) are known to be associated with anaplastic lymphoma kinase (ALK) gene rearrangements. Other molecular alterations such as ROS proto-oncogene 1, receptor tyrosine kinase (ROS1), neurotrophic tyrosine receptor kinase (NTRK), and platelet-derived growth factor receptor (PDGFR) have also been identified in IMTs. Although there are no randomized controlled clinical trials comparing chemotherapy, tyrosine kinase inhibitors (TKIs), or other systemic therapies, the literature demonstrates the use of ALK-targeted TKIs as an effective strategy for the treatment of locally advanced or metastatic ALK-rearranged IMTs. This case report describes a patient with an ALK-rearranged locally advanced pulmonary IMT who was treated with neoadjuvant-intent crizotinib. The patient had a very favorable response to therapy, and surgery was declined. It is difficult to determine the duration and sequencing of TKI use in these settings as there is little published data to guide decisions. This report also includes a comprehensive compilation of published IMT cases with molecular alterations treated with systemic therapy, which also highlighted the duration of therapies and clinical outcomes.

Infantile Inflammatory Myofibroblastic Tumor of Spleen

Background: Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm with unknown etiology and recurrent potential. They are widely reported in children and young adults. Nearly 50% of inflammatory myofibroblastic tumor harbor rearrangement in anaplastic lymphoma kinase (ALK) gene with the majority expressing ALK protein. ALK-negative IMTs harbor alteration in ROS1 gene in a subset of cases. Few reports have shown association of IMT with Epstein-Barr virus (EBV). Case report: We report a case of IMT of the spleen in an 18-month-old infant presenting with abdominal distention and failure to thrive. Workup for ALK-1, ROS1, and EBV small-encoded RNA in-situ hybridization using immunohistochemistry was negative. Conclusions: IMT can arise in an infant spleen.

Cutaneous Inflammatory Myofibroblastic Tumor with CARS-ALK Fusion: Case Report and Literature Review

Cutaneous inflammatory myofibroblastic tumors (IMT) constitute a rare entity, generating a diagnostic pitfall when diagnosing spindle cell proliferation within the dermis. Raising awareness of this tumor among dermatopathologists remains vital in differentiating it from common cutaneous tumors such as fibrous histiocytoma, atypical fibroxanthoma, melanoma, poorly differentiated carcinoma, and other more aggressive tumors. Accurate diagnosis of IMT aid in ensuring appropriate management and follow-up for patients while preventing unnecessary harm and overtreatment. Here we report a case of a 38-year-old female with a painless, slow-growing nodule of the left posterior scalp initially diagnosed as a dermatofibroma. The histological examination revealed an ill-defined dermal nodule of spindled cells without connection or infiltration of the epidermis. At high power, the cells were arranged in fascicles with a prominent background of lymphocytic infiltrate. Immunohistochemical analysis showed strong diffuse immunoreactivity for anaplastic lymphoma kinase (ALK), targeted RNA sequencing identified a CARS-ALK fusion ultimately confirming the accurate diagnosis of a cutaneous IMT. This article is protected by copyright. All rights reserved.

Isolated Otologic Involvement of IgG4 Related Disease: A Case Report and Review of Literature

Immunoglobulin G4 related disease (IgG4-RD) is a systemic autoimmune disease process that classically presents with multi-organ involvement; however isolated involvement of various structures within the body has also been described. Histopathologic examination is considered the gold standard for diagnosis. Glucocorticoids are well established as first-line treatment, but relapses are common, and consultation with rheumatology, immunology, and/or oncology teams is almost always warranted for proper medical management and disease maintenance. Given the relative infancy of IgG4-RD as an accepted diagnosis and the overall rarity of the disease, much still needs to be learned about this variable disease process. We present this case of isolated otologic and lateral skull base involvement of IgG4-RD to contribute to the understanding of this exceedingly rare clinical entity.

Case Report: Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Application in Intraperitoneally Disseminated Inflammatory Myofibroblastic Tumor and in the Youngest Patient in the World: New Indication and Modification of Technique

Introduction: Peritoneal metastases occur in cancers that spread to the peritoneal cavity and indicate the advanced stage of the disease. In children they are mainly seen in sarcomas, Gastrointestinal Stromal Tumors and primary disseminated ovarian tumors. Inflammatory Myofibroblastic Tumor (IMT) is a very rare lesion, characterized by an unpredictable clinical course. The absorption of chemotherapeutic agents through the peritoneal-plasma barrier (PPB) is minimized, thus HIPEC procedure limits the systemic exposure to chemotherapy and permits the administration of its higher doses. The main purpose of HIPEC is to remove the visible macroscopic disease in order to achieve complete cytoreduction (CRS).

HIPEC Procedure in Children: Several papers deal with the CRS and HIPEC in children and adolescents, however pediatric experience is still limited. Thus far, the HIPEC procedure has been carried out on patients over 2 years old. The most common indication for the surgery and the best outcome was experienced by patients with desmoplastic small round cell tumor (DSRCT). Most patients received intraperitoneal cisplatin.

HIPEC Modification: A 5-month-old infant was admitted to the Department of Pediatric Oncology due to the abdominal distention and blood in the stool. The Computed Tomography (CT) revealed a solid-cystic mass in the right abdominal area. The primary tumor and numerous peritoneal metastasis were removed and the Inflammatory Myofibroblastic Tumor (IMT) was diagnosed. The patient underwent subsequently CRS and modified HIPEC procedure. To avoid overheating of the infant, the intraperitoneal normothermic chemoperfusion was performed. Due to the low body weight a modified dosage of intraperitoneal doxorubicin was used. The child underwent standard postoperative chemotherapy and received crizotinib therapy. At 12 months follow-up since treatment completion the patient remains in complete remission. To our knowledge this is the youngest patient, the only infant and the first pediatric patient with IMT who underwent the modified HIPEC procedure in the world.

Conclusions: CRS and HIPEC is technically possible also in infants. For its safe course patients selection and technique modification are necessary. Use of HIPEC should be also considered in intraperitoneally disseminated IMT. A complete cytoreductive surgery as the first HIPEC step seems to be the key factor in survival.

Non-neoplastic inflammatory pseudotumor of the lung after immunotherapy for melanoma: A diagnostic pitfall on fine needle aspiration biopsy of lung

Nivolumab is commonly used as monotherapy or in combination therapy for management of locally advanced or metastatic melanoma; however, it is also associated with immunotherapy-related adverse events concerning for disease progression or tumor flare reaction. This report presents a case of a non-neoplastic pseudotumor of the lung initially mistaken for malignancy that occurred in a patient receiving adjuvant nivolumab therapy following complete resection of stage IIIB melanoma. The diagnosis was made by lung biopsy and confirmed by a wedge resection, with findings consistent with organizing pneumonia type of pulmonary inflammatory pseudotumor rather than malignancy.

Complicated course of biliary inflammatory myofibroblastic tumor mimicking hilar cholangiocarcinoma: A case report and literature review

BACKGROUND

The inflammatory myofibroblastic tumor (IMT) is a rare, idiopathic, usually benign, mass-forming disease with myofibroblastic proliferation and a varying amount of inflammatory cells. Although it can affect various organs, the biliary tract is a rare localization of primary IMT, clinically, endoscopically and radiologically imitating cholangiocarcinoma. The treatment options are based only on clinical practice experience.

CASE SUMMARY

A 70-year-old woman was referred to our center due to progressive fatigue, weight loss, abdominal pain, night sweats, and elevated liver enzymes. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography (ERCP) revealed proximal common hepatic duct and hilar biliary strictures extending bilaterally to lobular bile ducts. Although initial clinical, endoscopic and radiological signs were typical for hilar cholangiocarcinoma, histological examination showed no signs of malignancy. In total, 8 biopsies using different approaches were performed (several biopsies from dominant stricture during ERCP and direct cholangioscopy; ultrasound-guided liver biopsy; diagnostic laparoscopy with liver and lymph node biopsies). Histological examination revealed signs of IMT, and the final diagnosis of biliary IMT was stated. Although IMT is usually a benign disease, in our case, it was complicated. All pharmacological treatment measures were ineffective. The patient still needs permanent stenting, suffers from recurrent infections and mechanical jaundice. Despite that, the patient already survived 24 mo.

CONCLUSION

IMT presenting with hilar biliary strictures is a unique diagnostic and clinical challenge as it is indistinguishable from cholangiocarcinoma, and there are no evidence-based treatment options. Our goal is to increase the understanding of this rare disease and its possible course.

ALK-negative lung inflammatory myofibroblastic tumor in a young adult: A case report and literature review of molecular alterations

RATIONALE

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor that is prevalent among children and adolescents. Surgery is the most important therapeutic approach for IMT and complete resection is recommended. Although 50% of IMTs show anaplastic lymphoma kinase (ALK) rearrangements, crizotinib has proven an effective therapeutic approach. However, the genetic landscape of this tumor is still not fully understood and treatment options are limited, especially in the majority of ALK-negative tumors.

PATIENT CONCERNS

We describe the clinical case of a healthy 18-year-old female in whom a pulmonary nodule was incidentally detected.

DIAGNOSES

Following a small increase in the size of the nodule, the patient underwent both 18FDG-PET/CT and 68Ga-PET/CT, resulting in a suspicion of bronchial hamartoma.

INTERVENTIONS

The patient underwent surgery and a salivary gland-like lung tumor was diagnosed.

OUTCOMES

After surgery, the patient was referred to our cancer center, where a review of the histology slides gave a final diagnosis of ALK-negative lung IMT. Given the histology, it was decided not to administer adjuvant therapy and the patient was placed in a 3-monthly follow-up program. The patient is still disease-free 2 years post-surgery.

LESSONS

Although there is no standard of care for the treatment of IMT, identifying genomic alterations could help to redefine the management of patients with negative-ALK disease. Our review of the literature on IMT and other kinase fusions revealed, in addition to ALK rearrangements, the potential association of ROS1, NTRK, RET, or PDGFR beta alterations with the tumor.

Near-complete response to low-dose ceritinib in recurrent infantile inflammatory myofibroblastic tumour

Background

Infantile inflammatory myofibroblastic tumour (IMT) is rare and the majority are driven by anaplastic lymphoma kinase (ALK) rearrangements. Previous literature on the use of ALK inhibitors in paediatric IMTs is extremely limited with no published literature on the use in infants. Crizotinib and ceritinib are two ALK inhibitors which are available and have been used in IMTs; however, ceritinib is much more affordable in the low- and middle-income country (LMIC) setting than crizotinib.

Case

An 11-month-old child, who had undergone surgery for mesenteric IMT at the age of 3 months, had an unresectable recurrence with soft tissue deposits in the subdiaphragmatic location abutting the spleen and paravesical location. As surgery would have entailed splenectomy and partial cystectomy, she was treated with low-dose ceritinib (300 mg/m2/day) with which she had a near-complete response without any toxicity.

Discussion and conclusion

This is the first report of the use of ceritinib at a lower dose for infantile IMT having immense practical applications for the low- and middle-income setting.

Infantile inflammatory myofibroblastic tumors: clinicopathological and molecular characterization of 12 cases

Inflammatory myofibroblastic tumors arising in infants are rare, poorly investigated and mostly reported as isolated cases or as a part of larger series thus, their clinicopathological and molecular features are essentially unknown. Archival files from two large pediatric institutions and a tumor registry were queried for pediatric inflammatory myofibroblastic tumors. Available material from patients ≤12 months of age was reviewed. Additional immunostains (ALK-1, D240, WT1) and ALK-FISH studies were performed as needed. Targeted anchored multiplex PCR with next-generation sequencing was done in all cases. A total of 12 of 131 infantile cases (mean 5.5 months) were identified (M:F of 2:1). Anatomic locations included intestinal/mesenteric (n = 6), head/neck (n = 3), and viscera (n = 3). Half of tumors showed a hypocellular myxoid pattern, perivascular condensation, and prominent vasculature with vague glomeruloid structures present in four of them. The remaining cases exhibited a more cellular pattern with minimal myxoid component. ALK-1 immunohistochemistry was positive in most cases (11/12) with cytoplasmic-diffuse (n = 6), cytoplasmic-granular (n = 2), and dot-like (n = 3) staining patterns. ALK fusion partners identified in five cases included EML4, TPM4, RANBP2, and a novel KLC1. Three inflammatory myofibroblastic tumors showed fusions with other kinases including TFG-ROS1 and novel FN1-ROS1 and RBPMS-NTRK3 rearrangements. Favorable outcome was documented in most cases (10/11) with available follow-up (median 17 months) while three patients were successfully treated with crizotinib. In summary, infantile inflammatory myofibroblastic tumors are rare and can exhibit paucicellular, extensively myxoid/vascular morphology with peculiar immunophenotype mimicking other mesenchymal or vascular lesions. All tumors harbored kinase fusions involving ALK, ROS1, and NTRK3 including three novel fusion partners (KLC1, FN1, and RBPMS, respectively). A favorable response to crizotinib seen in three cases supports its potential use in infants as seen in older patients. Awareness of these unusual morphologic, immunophenotypic, and molecular features is critical for appropriate diagnosis and optimized targeted therapy.

Aggressive Inflammatory Myofibroblastic Tumor without Anaplastic Lymphoma Kinase Gene Rearrangement in the Rectum with Liver Metastasis

Inflammatory myofibroblastic tumor is a rare intermediate-grade tumor. We herein report the case of an 81-year-old man with rectal ulceration and abnormal retroperitoneal soft tissue with a high serum level of IgG4. The administration of prednisolone reduced the retroperitoneal lesion; however, the rectal ulceration expanded. Surgical resection was performed. A histopathological examination revealed proliferating spindle cells accompanied by inflammatory cells and plasma cells. Liver metastasis emerged two months after surgical resection, and the histology of the proliferating spindle cells sampled by a fine-needle biopsy was similar to that of the rectal tissue. The patient ultimately died of inflammatory myofibroblastic tumor.

Recurrent metastatic primary inflammatory myofibroblast tumour of the gallbladder following pancreaticoduodenectomy

Inflammatory myofibroblast tumour (IMT) is an uncommon soft tissue tumour with an unpredictable clinical course: mostly benign, occasionally locally aggressive and rarely capable of metastasis. Diagnosed mainly in the mesentery, omentum, retroperitoneum, pelvis and lungs, IMT is extremely rare as a primary gallbladder tumour. Despite improved radiographical capabilities, differentiating the tumour from other more common causes of gallbladder neoplasms necessitates histopathological and immunohistochemistry tests. Once diagnosed, malignant potential should be taken into consideration, striving for an en bloc R0 resection and postoperative long-term follow-up with routine ancillary imaging. The authors present the case of a recurrent primary IMT of the gallbladder, after two surgical treatments, including a pancreaticoduodenectomy. Now 3 years after initial diagnoses the patient is asymptomatic, but has developed local and distant metastases and is being treated with systemic corticosteroid.

Morphologic Overlap Between Inflammatory Myofibroblastic Tumor and IgG4-related Disease: Lessons From Next-generation Sequencing

Inflammatory myofibroblastic tumor (IMT), a locally aggressive neoplasm capable of metastasis, may show an immunoglobulin (Ig)G4-rich lymphoplasmacytic infiltrate. Prior reports suggest that storiform-fibrosis and obliterative phlebitis aid in the distinction of IMT from IgG4-related diseases. Herein, we highlight the morphologic overlap between the 2 diseases, and emphasize the importance of a multiplex fusion assay in the distinction of IgG4-related disease (IgG4-RD) from IMT. We identified 7 IMTs with morphologic and immunohistochemical features of IgG4-RD; 3 patients were originally diagnosed with IgG4-RD. Demographic, clinical and morphologic data was recorded. We also reevaluated 56 patients with IgG4-RD. We performed immunohistochemistry for IgG4, IgG, ALK, and ROS1. In situ hybridization for IgG4 and IgG was performed in selected cases. A multiplex next-generation sequencing-based RNA assay for gene fusions was performed to detect all known IMT-related gene fusions. All 7 IMTs showed a dense lymphoplasmacytic infiltrate and storiform-type fibrosis, with obliterative phlebitis noted in 3 cases. The neoplastic stromal cells constituted <5% of overall cellularity and stromal atypia was either absent or focal and mild. Elevated numbers of IgG4 positive cells and increased IgG4 to IgG ratio was identified in all cases. Four cases showed ALK related abnormalities: 3 fusions and one alternative transcription initiation; while 2 patients showed ROS1 and NTRK3 fusions. One tumor was negative for known IMT-related gene fusions. All 56 IgG4-RD cases were negative for ALK and ROS1 on immunohistochemistry; 6 cases were negative on the fusion assay. Highly inflamed IMTs are indistinguishable from IgG4-RD both histologically and on immunohistochemistry for IgG4. We advocate scrutinizing patients with presumptive single organ IgG4-RD for IMT and the diagnostic algorithm should include ALK and ROS1 immunohistochemistry and, in selected cases, a next-generation sequencing-based fusion assay that covers known IMT-associated gene fusions.

Successful treatment based on molecular biological assessment of invasive anaplastic lymphoma kinase-positive inflammatory myofibroblastic tumor of the lung

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) of the lung is rare. This disease often shows neoplastic features with anaplastic lymphoma kinase positiveness as well as inflammatory features, such as steroid-responsive immunoglobulin G4 (IgG4)-related sclerosing disease. Since many cases have been reported as advanced, various treatment strategies should be considered based on clinical and biological features of each case.

CASE PRESENTATION

We report a 49-year-old male with IMT, which seemed invading the left atrium from preoperative imaging modalities. Serological and pathological examinations from the biopsy specimen revealed high expression of anaplastic lymphoma kinase expression in the tumor. On the other hand, IgG4/IgG ration in the tumor was small, where a therapeutic effect of steroid was not expected, leading to surgical treatment rather than a steroid administration. The tumor was completely resected en bloc with the right lower lobe of the lung and a part of the left atrium. The postoperative course of the patient was uneventful. The patient has remained recurrence free over 5 years from the surgery.

CONCLUSION

In this case, preoperative biological assessment prior to the treatment led to a good clinical course. We believe that molecular biological examination is important in the determination of treatment strategy for this rare disease as well as imaging modalities.

Can colonic inflammatory polyp with numerous immunoglobulin G4-positive plasma cells represent a colonic manifestation of immunoglobulin G4-related disease? A case report

We present an asymptomatic case of a 79-year-old Japanese man who had a 6 mm colonic inflammatory polyp with numerous immunoglobulin G4 (IgG4)-positive plasma cells. No symptoms or abnormal laboratory data, such as changes in serum IgG4 levels, were found at the time of diagnosis or during the 1 year of follow-up thereafter. Additionally, no diffuse/localized swelling or masses were found in organs, except for colonic polyps, by abdominal computed tomography 1 year prior to the polypectomy. Inflammatory myofibroblastic tumor was unlikely from the lack of spindle cell proliferation and ALK immunoreactivity. This is the first case of this colonic polyp in an asymptomatic person. This polyp could be probable for single organ manifestation of IgG4-related disease (IgG4-RD), according to the comprehensive diagnostic criteria for IgG4-RD published in 2012; however, colonic manifestation of IgG4-RD has not been clarified owing to its rarity, and colon-specific criteria for IgG4-RD have not been proposed. Thus, we could not definitively establish the colonic polyp as IgG4-RD. Therefore, careful clinicopathological evaluation is needed to reveal whether this colonic polyp represents a nonspecific inflammatory response or an early manifestation of IgG4-RD.

The histological diagnosis of IgG4-related disease on small biopsies: challenges and pitfalls

AIMS

The pathological diagnosis of IgG4-related disease (IgG4-RD) relies on histology, IgG4-positive cells, and an increased IgG4/IgG ratio. Small biopsies from patients with a presumptive diagnosis of IgG4-RD often fail to meet consensus histological criteria. The aims of this study were to evaluate consecutive small biopsies from patients with a presumptive diagnosis of IgG4-RD, and to assess the significance of the pathological findings.

METHODS AND RESULTS

We evaluated 55 small biopsies from patients with a presumptive diagnosis of IgG4-RD. The retrospective cohort comprised 71 patients with IgG4-RD and 57 mimics. We performed immunohistochemistry (IHC) and in-situ hybridisation (ISH) for IgG4 and IgG. Twenty-six patients from the prospective cohort met the histological criteria for IgG4-RD (definite); 29 patients lacked one or more pathological features (borderline). Twenty biopsies (36%) lacked both storiform fibrosis and obliterative phlebitis, and nine (16%) lacked an increase in the number of IgG4-positive plasma cells. Ninety-three per cent of patients showed an IgG4/total IgG ratio of >40% (>30% by ISH). There were no differences in the incidence of multiorgan disease (P = 0.9), serum IgG4 levels (P = 0.6) and response to therapy between the definite and borderline groups. A strong correlation (Pearson 0.77) between the IHC and ISH platforms was noted with regard to the IgG4/total IgG ratio.

CONCLUSION

Patients with a presumptive diagnosis of IgG4-RD but lacking the characteristic pathological features of this disease appear to be clinically similar to those who meet the current pathological criteria. An elevated IgG4/total IgG ratio is the most sensitive pathological feature, and ISH provides a robust quantification platform. We recommend evaluating tumefactive lymphoplasmacytic infiltrates with an increased IgG4/IgG ratio, regardless of histological features, for IgG4-RD.

Expanding the Molecular Characterization of Thoracic Inflammatory Myofibroblastic Tumors beyond ALK Gene Rearrangements

INTRODUCTION

Half of inflammatory myofibroblastic tumors (IMTs) regardless of anatomic location harbor anaplastic lymphoma kinase gene (ALK) rearrangements and overexpress anaplastic lymphoma kinase protein. The wide application of next-generation sequencing and the clinical benefit to tyrosine kinase inhibitors have opened new opportunities for investigation of ALK-negative IMTs.

METHODS

In this study, we have investigated a series of pediatric and adult thoracic IMTs for abnormalities in a wide spectrum of actionable kinases by applying a variety of molecular and next-generation sequencing techniques, including fluorescence in situ hybridization (FISH), targeted RNA sequencing, and NanoString assay.

RESULTS

There were 33 patients with thoracic IMTs, including five children; their mean age was 37. The tumors showed a monomorphic spindle cell phenotype, except for one with an epithelioid morphologic pattern and moderate to severe atypia. By immunohistochemistry, 24 tumors were ALK positive, and 19 of the 24 showed ALK rearrangements and one ret proto-oncogene gene (RET) rearrangement by FISH. RNA sequencing was performed in the remaining four cases lacking ALK abnormalities by FISH, revealing ALK fusions involving tropomyosin 4 gene (TMP4) and echinoderm microtubule associated protein like 4 gene (EML4) as partner in three cases. NanoString assay was performed in the remaining case, revealing ALK alternative transcription initiation (ALK^ATI). Nine cases lacking ALK abnormalities were further tested by FISH or targeted RNA sequencing, revealing ROS1 rearrangement in six cases and ETS variant 6 gene (ETV6)-neurotrophic receptor tyrosine kinase 3 gene (NTRK3) fusion in three cases, respectively.

CONCLUSIONS

By using a battery of complementary molecular techniques, we have shown that all the thoracic IMTs harbored a tyrosine kinase abnormality, with 30% involving a kinase gene other than ALK, including ROS1, NTRK3, and RET gene fusions. We have also described for the first time ALK^ATI-induced ALK oncogenic activation in IMTs.

Reprint of: Pathologic manifestations of Immunoglobulin(Ig)G4-related lung disease

Immunoglobulin(Ig)G4-related disease (IgG4-RD) is a fibroinflammatory condition that can affect virtually any organ and usually presents as tumefactive lesions involving multiple sites. Characteristic histopathology of IgG4-RD consists of dense lymphoplasmacytic infiltrate, fibrosis (often in storiform pattern), and obliterative phlebitis, accompanied by tissue infiltration of IgG4-positive plasma cells with or without elevation of serum IgG4 level. Despite a general similarity in the morphologic manifestations of IgG4-RD, site-specific unique morphologic features have been described in some organs including the lung. Compared with other sites, pulmonary involvement by IgG4-RD has been recognized more recently, and lung biopsy interpretation for this condition is often challenging, as both a relative paucity of pathognomonic features and a plethora of overlapping findings with other fibroinflammatory processes of the lung. This review is focused on the morphologic spectrum of IgG4-related lung disease documented in the current literature and on the pertinent issues in the differential diagnoses with other conditions encountered in the lung.

IgG4-related disease: review of the histopathologic features, differential diagnosis, and therapeutic approach

Immunoglobulin G4-related disease (IgG4-RD) is an uncommon disorder that demonstrates characteristic clinicopathologic features including sclerosing lesions with storiform fibrosis, increased IgG4+ plasma cells with an increased IgG4+/IgG+ plasma cell ratio, obliterative phlebitis, and often an increased serum IgG4 level. This review summarizes the characteristic histopathologic and clinical features of IgG4-RD with detailed discussion of the histopathologic characteristics of the most commonly involved anatomic sites. We also present recent advances in our understanding of the pathophysiologic mechanisms of IgG4-RD and discuss updates on the treatment, prognosis, and outcomes of this rare disease, including discussion of the possible association between IgG4-RD and malignancy.

Anaplastic lymphoma kinase-negative uterine inflammatory myofibroblastic tumor containing the ETV6-NTRK3 fusion gene: a case report

Inflammatory myofibroblastic tumors (IMTs) are neoplasms with low malignant potential, and the most common tumor in the lung and orbit. Their occurrence in the uterus is rare. Approximately 50% of IMT patients have anaplastic lymphoma kinase gene (ALK) rearrangements. Recent studies described novel fusions involving ROS1, platelet-derived growth factor receptor beta (PDGFR-β), and ETS translocation variant (ETV6) genes in a subset of ALK-negative patients. We report a 44-year-old woman with anemia and uterine IMT. Ultrasonography and magnetic resonance imaging revealed a myxoid degenerative myoma-like mass, 7.4 cm in maximum diameter, on the left uterine side wall. Hysterectomy was performed as a definitive treatment. Microscopic examination revealed spindle cell proliferation with numerous lymphocytes and plasma cells. Immunohistochemically, the spindle cells were negative for ALK-1, desmin, and smooth muscle actin. The pathological diagnosis was IMT arising from the uterus. Fluorescence in situ hybridization demonstrated an ETV6–neurotrophic tyrosine kinase, receptor, type 3 gene (NTRK3) translocation but no ALK, ROS1, or PDGFR-β translocations. Lung and abdomen computed tomography at 31 months postoperatively revealed no disease recurrence. This association of an ETV6–NTRK3 fusion oncogene with an ALK-negative uterine IMT increases our understanding of this neoplasm, which may help the development of specific therapies.

Inflammatory Myofibroblastic Tumor of the Tongue. Report of a Pediatric Case and Review of the Literature

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) is an uncommon mesenchymal lesion composed of myofibroblastic and fibroblastic spindle cells, accompanied by inflammatory infiltration. IMT may occur in the tongue. Five cases have been previously reported at this site.

CASE REPORT

An inflammatory myofibroblastic tumor arose in the tongue of a 10 month old infant, confirmed by anaplastic lymphoma kinase (ALK) immunohistochemical staining and the clinical response to the tyrosine kinase inhibitor.

CONCLUSIONS

IMT can occur in the tongue. This report highlights the differential diagnosis of IMT. ALK staining is both a helpful diagnostic marker and a predictive marker for targeted therapy in this tumor type.

Testicular Inflammatory Myofibroblastic Tumor: A Known Entity at a Very Rare Site

Inflammatory myofibroblastic tumors (IMT) are distinctive lesions of unknown etiology, composed of myofibroblastic spindle cells with an associated inflammatory background. They can occur in a wide age range and at all anatomic sites, but most frequently they can be observed in the lung (especially in pediatric cases), abdomen, or retroperitoneum. The urinary bladder is one of the most common sites in urological cases. We present a very rare case of IMT of the testis. Clinically, a 40-year-old patient showed a palpable painless lesion of the right testis. Ultrasound examination showed two solid intratesticular foci. During surgical intervention, the intraoperative frozen section revealed mesenchymal tumors admixed with an uncommon inflammatory infiltrate, consistent with a reorganized abscess. Despite the benign result, orchiectomy was performed due to the multifocal presentation and the large size of 3 cm. The final diagnosis was IMT without ALK-rearrangement. Incomplete resection increases the risk of local relapses to 30%. In this case, a complete resection could be achieved and the patient is free of tumor 15 months later.

IgG4-related Disease and the Liver

Pathologists are likely to encounter IgG4-related disease in several organ systems. This article focuses on helping pathologists diagnose IgG4-related disease in the hepatobiliary system. Missing the diagnosis can result in unnecessary organ damage and/or unnecessary surgical and cancer therapy. In the liver, tumefactive lesion(s) involving the bile ducts with storiform fibrosis and an IgG4-enriched lymphoplasmacytic infiltrate are highly concerning for IgG4-related disease. The recent identification of oligoclonal populations of T cells and B cells in IgG4-related disease may lead to molecular tests, new therapeutics, and a greater mechanistic understanding of the disease.

A Comparative Study of Inflammatory Myofibroblastic Tumors and Tumefactive IgG4-related Inflammatory Lesions: the Relevance of IgG4 Plasma Cells

IgG4-related disease is a recently recognized systemic condition characterized by tumefactive lesions at various sites. Inflammatory pseudotumor (IPT), a tumefactive mass lesion with an unknown etiology, belongs to the spectrum of IgG4-related disease. Inflammatory myofibroblastic tumor (IMT), previously considered under the umbrella of IPT, is now classified as a clonal neoplasm. Previously, both the terms were used interchangeably, because of overlapping morphologic features. This study was carried out to compare the morphologic and the immunohistochemical features of these entities and to study the role of IgG4 in their pathogenesis. Thirty-nine cases comprising of IMT (n=18) and IPT (n=21) were retrieved, and their clinical, morphologic, and immunohistochemical features were studied. IMT was more common in children as compared with IPT. IMT cases showed the proliferation of myofibroblastic cells accompanied by a variable inflammatory infiltrate, whereas IPT cases showed predominantly stromal fibrosis and a lymphoplasmacytic infiltrate with a subset of cases showing a storiform fibrosis and obliterative phlebitis. Anaplastic lymphoma kinase-1 (ALK-1) was positive in 12 of the 18 (66.7%) IMT cases, whereas none of the IPT cases showed ALK-1 immunoreactivity. IPT cases showed significantly increased IgG4+ plasma cells (mean, 127.8/high-power fields vs. 17.8/high-power fields) and a higher IgG4/IgG ratio (mean, 48.2% vs. 10.7%) as compared with IMT. Fluorescence in situ hybridization analysis was positive for ALK rearrangement in 6 of the 9 IMT cases tested. In conclusion, most of the IPT cases can be considered as IgG4 related on the basis of their histopathologic features and immunohistochemistry criteria. However, IMT represents a myofibroblastic neoplasm with ALK-1 overexpression and is clearly not IgG4 related.

Pulmonary inflammatory myofibroblastic tumor versus IgG4-related inflammatory pseudotumor: differential diagnosis based on a case series

BACKGROUND

Pulmonary inflammatory myofibroblastic tumor (IMT) has been considered as a synonym for inflammatory pseudotumor (IPT) for a long time. Recent studies have indicated that IMT and IgG4-related IPT are distinct diseases. However, no consensus criteria have been recommended. Here we propose a set of criteria for the differential diagnosis.

METHODS

Twenty-six archived IMT and IgG4-related IPT samples were examined for histological characteristics and the expression of IgG, IgG4, SMA and ALK-1. Based on our proposed criteria, we reclassified the cases into either IMT or IgG4-related IPT group and compared the clinicopathological features, laboratory findings, overall survivals (OS) and disease-free survivals between groups to validate the effectiveness and dependability of the diagnostic criteria.

RESULTS

The average age of IgG4-related IPT group was higher than IMTs (48.82 vs. 39.22 years, P=0.031). In IMT group, tumors were characterized by bigger tumor sizes (3.47 vs. 2.22 cm, P=0.007), diffuse and total destroyed alveoli (88.89% vs. 17.65%, P=0.002), fewer lymphoid follicles (1.6/HPF vs. 3.0/HPF, P=0.045) and lower expression of IgG (74.7/HPF vs. 149.1/HPF; P<0.001). As an exclusion criterion of IgG4-related IPT, ALK-positivity was correlated with the higher cytological atypia (mean 3.7/HPF, P<0.001) and lesser lymphoid follicles (mean 1.2/HPF, P=0.021). And it's the first study to show the liner positive correlation between the lymphocytes + plasma cells count and IgG4-positive plasma cells count in these lesions (r=0.914, P<0.001). The negative correlation between the IgG4-positive plasma cells count and the expression of ALK-1 are reported for the first time as well (rs=-0.632, P=0.001). However, despite two patients with recurrence or metastasis were divided into IMT group, only borderline values were detected in the survival analysis (OS 88.89% vs. 100%, P=0.197, DFS 77.78% vs. 100.00%; P=0.056).

CONCLUSIONS

The significant differences of clinicopathological characteristics between the IMTs and IgG4-related IPTs indicated that a combination of lymphocytes + plasma cells count, cytological atypia, IgG4 and ALK-1 staining will be helpful in differential diagnosis.

Indolent lung opacity: Ten years follow-up of pulmonary inflammatory pseudo-tumor

Inflammatory pseudotumor (IPT) has always been considered a diagnostic challenge. Its rarity and resemblance to other more common pathological entities imposes that neither clinical nor radiological characteristics can lead to a definitive diagnosis. The surgical excision of the lesion is the ultimate approach for accurate diagnosis and cure. Moreover the true nature of IPT, its origin as a neoplastic entity or an over-reactive inflammatory reaction to an unknown trigger, has been a long debated matter. Surgery remains the treatment of choice. IPT is mostly an indolent disease with minimal morbidity and mortality. Local invasion and metastasis predict a poor prognosis. We hereby present a unique case of pulmonary IPT that was surgically excised, but recurred contralaterally, shortly thereafter. Despite no medical or surgical treatment for ten years, the lesion has remained stable in size, with neither symptoms nor extra-pulmonary manifestations.

An isolated inflammatory myofibroblastic tumor of adrenal gland

Inflammatory myofibroblastic tumor (IMT) is an uncommon lesion that shows a wide range of anatomic distribution. The adrenal gland, however, is a distinctly rare site of occurrence. To date, only a few cases of IMT arising in the adrenal gland have been reported in the English literature. Here, we report another case of isolated adrenal IMT. A 34-year-old man presented to the emergency department with a complaint of a sudden severe right-sided back pain. Subsequent computed tomographic scan imaging studies demonstrated a large right adrenal mass associated with a hematoma. The right adrenal gland was resected. Microscopic examination revealed an encapsulated cellular spindle cell proliferation with a prominent inflammatory infiltrate. Immunohistochemically, those spindle cells were diffusely and strongly positive for anaplastic lymphoma kinase-1, and focally and weakly positive for smooth muscle actin. S-100 protein and cytokeratin were negative. The findings were consistent with IMT arising from the adrenal gland. Although IMTs in the adrenal gland are rare, they should be considered in the differential diagnosis of adrenal masses. The clinical behavior of IMTs in general is currently indeterminate and a close clinical follow-up is recommended. The behavior of adrenal IMTs remains uncertain because of rare reported cases and lack of long-term follow-up. Further follow-up of reported cases and recognition of additional new cases is warranted to unmask the true biological behavior of adrenal IMTs.

Inflammatory Myofibroblastic Tumour of Thyroid with its Prominent Spindle Cell Pattern: A Rare Case Report

Inflammatory myofibroblastic tumour of thyroid is very rare. Only 18 cases reported so far. Here we report a case of Inflammatory myofibroblastic tumour with its prominent spindle cell (fibrohistiocytic) pattern in a 61-year-old male patient. The dominant histological pattern in our case was myofibroblastic in contrast to prominent lymphoplasmocytic pattern in other previously reported cases. The tumour was strongly positive for vimentin, Anaplastic lymphoma kinase and showed focal positivity for Smooth Muscle Actin. The patient was treated with total thyroidectomy and he is comfortable after surgery.

Inflammatory Pseudotumor (IPT) and Inflammatory Myofibroblastic Tumor (IMT): A Representative Literature Review Occasioned by a Rare IMT of the Transverse Colon in a 9-year-old Child

Aims and Background

Inflammatory pseudotumor (IPT) and inflammatory myofibroblastic tumor (IMT) represent different entities. However, it is only in recent years that this has been taken into increasing consideration. Some authors still use both terms synonymously or interchangeably. Inflammatory myofibroblastic tumor is a real neoplasm because of the proliferation of myofibroblastic cells. Inflammatory pseudotumor is a more inflammatory reactive or regenerative entity and shows an overlapping with immunoglobulin G4-related disease.

Methods and Study Design

To analyze the current situation, 443 publications from the last 5 years (2009 to February 2014) were included. Reports involved 938 patients and 956 organ sites. The age distribution is twin peaked with one maximum in childhood and the other between 50 and 60 years of age. This distribution is questionable due to the more frequent occurrence of IPT in the liver and of IMT in the lung. Inflammatory pseudotumors mainly occur in older patients; IMTs in children and young adults.

Results and Conclusions

The liver and biliary tract were the most commonly affected of all body regions, at 32%. This was followed by the lung, including the respiratory tract, at 27%, and by the gastrointestinal tract, at 10%. Lesions of the large bowel, as in the present case of a 9-year-old boy, are very rare. There were organ-related as well as nonspecific clinical symptoms, such as fever, weight loss, and fatigue. Laboratory test results revealed anemia and elevated inflammation-dependent parameters. The patterns in medical imaging are variable and nonspecific. Morphology often suggests a malignant process. For this reason, therapy in most cases is surgical, but this is required more often in IMTs. Many IPTs could be treated conservatively.

Coexistence of gastrointestinal stromal tumor and inflammatory myofibroblastic tumor of the stomach presenting as a collision tumor: first case report and literature review

Collision tumors of the stomach are rare. We report on a case of a collision tumor consisting of a gastrointestinal stromal tumor (GIST) and an inflammatory myofibroblastic tumor (IMT) of the stomach in a 16-year-old female. A polypoid mass located in the distal body of the stomach was observed on abdominal computed tomography. Laparoscopic wedge resection of the stomach and 4d lymph node biopsy was performed. On gross examination, a protruding submucosal mass, measuring 4 × 3.5 × 2.5 cm in size, was detected. Histological examination showed two distinct GIST and IMT component presenting a collision tumor. The small nodular area, composed of CD117-positive spindle cells, was typical of GIST, and the adjacent larger area, composed of myofibroblastic spindle cells with prominent chronic inflammatory cells infiltrate, mainly lymphocytes and plasma cells, had a characteristic appearance of IMT. The 4d lymph node showed metastatic inflammatory myofibroblastic tumor. To the best of our knowledge, this is the first case of a collision tumor consisting of a GIST and an IMT arising in the stomach.

IgG4-Related Disease of the Gastrointestinal Tract: A 21st Century Chameleon

CONTEXT

Immunoglobulin G4 (IgG4)-related disease is a systemic fibroinflammatory disease capable of affecting virtually any organ. Although the pancreas and hepatobiliary system are commonly affected, involvement of the tubular gut is unusual. The pancreatic manifestations of this disease (autoimmune pancreatitis) often mimic pancreatic carcinoma, whereas the hepatobiliary manifestations are mistaken for cholangiocarcinoma or primary sclerosing cholangitis. The characteristic histologic features include a dense lymphoplasmacytic infiltrate, storiform-type fibrosis, and obliterative phlebitis. An increase in IgG4(+) plasma cells and an IgG4 to IgG ratio of more than 40% are considered obligatory components of the diagnostic algorithm.

OBJECTIVE

To review the challenges associated with the diagnosis of IgG4-related disease of the gastrointestinal tract.

DATA SOURCES

A review of pertinent literature, along with the author's personal experience, based on institutional and consultation materials.

CONCLUSION

The complete spectrum of histologic changes is seldom captured in a biopsy specimen, and thus, the histopathology findings are best interpreted within the overall clinical context. Increased IgG4(+) plasma cells are identified in a variety of benign and malignant diseases of the gastrointestinal tract.

Molecular characterization of inflammatory myofibroblastic tumors with frequent ALK and ROS1 gene fusions and rare novel RET rearrangement

Approximately 50% of conventional inflammatory myofibroblastic tumors (IMTs) harbor ALK gene rearrangement and overexpress ALK. Recently, gene fusions involving other kinases have been implicated in the pathogenesis of IMT, including ROS1 and in 1 patient PDGFRB. However, it remains uncertain whether the emerging genotypes correlate with clinicopathologic characteristics of IMT. In this study, we expand the molecular investigation of IMT in a large cohort of different clinical presentations and analyze for potential genotype-phenotype associations. Criteria for inclusion in the study were typical morphology and tissue availability for molecular studies. The lack of ALK immunoreactivity was not an excluding factor. As overlapping gene fusions involving actionable kinases are emerging in both IMT and lung cancer, we set out to evaluate abnormalities in ALK, ROS1, PDGFRB, NTRK1, and RET by fluorescence in situ hybridization. In addition, next-generation paired-end RNA sequencing and FusionSeq algorithm was applied in 4 cases, which identified EML4-ALK fusions in 2 cases. Of the 62 IMTs (25 children and 37 adults), 35 (56%) showed ALK gene rearrangement. Of note, EML4-ALK inversion was noted in 7 (20%) cases, seen mainly in the lung and soft tissue of young children including 2 lesions from newborns. There were 6 (10%) ROS1-rearranged IMTs, all except 1 presenting in children, mainly in the lung and intra-abdominally and showed a distinctive fascicular growth of spindle cells with long cell processes, often positive for ROS1 immunohistochemistry. Two of the cases showed TFG-ROS1 fusions. Interestingly, 1 adult IMT revealed a RET gene rearrangement, a previously unreported finding. Our results show that 42/62 (68%) IMTs are characterized by kinase fusions, offering a rationale for targeted therapeutic strategies. Interestingly, 90% of fusion-negative IMTs were seen in adults, whereas >90% of pediatric IMT showed gene rearrangements. EML4-ALK inversion and ROS1 fusions emerge as common fusion abnormalities in IMT, closely recapitulating the pattern seen in lung cancer.

IgG4 related sclerosing mastitis: expanding the morphological spectrum of IgG4 related diseases

IgG4 related disease (IgG4RD) is a recently recognised condition characterised by mass forming lesions associated with storiform fibrosis, obliterative phlebitis, lymphoplasmacytic infiltrate rich in IgG4 positive plasma cells and elevated serum IgG4 levels. Although rare, mammary involvement has been reported as IgG4 related sclerosing mastitis, the morphological counterpart of a growing family of IgG4 related diseases. A total of 17 cases belonging to mass forming benign inflammatory breast lesions such as plasma cell mastitis, granulomatous lobular mastitis, non-specific mastitis and inflammatory pseudotumour were investigated as a possible member of IgG4 related sclerosing mastitis. Clinical, radiological, histopathological and immunohistochemistry findings were noted in all cases. Cases diagnosed as inflammatory pseudotumour showed all the histopathological features of IgG4RD along with increased number of IgG4 positive plasma cells and IgG4/IgG ratio >40%. However, only a few IgG4 positive cells were seen in plasma cell mastitis, granulomatous lobular mastitis and non-specific mastitis cases. These cases also did not fulfill the morphological criteria for the diagnosis of IgG4 related diseases. IgG4RD should be excluded in plasma cell rich lesions diagnosed on core biopsies by IgG4 immunostaining. This can avoid unnecessary surgery as IgG4 related diseases respond to simple and effective steroid treatment.

Bilateral inflammatory myofibroblastic tumor mastoiditis

BACKGROUND

Inflammatory myoblastic tumors (IMTs) are rare, mesenchymal neoplasms most commonly located in areas of previous inflammation. In the temporal bone, these tumors typically present as solitary, space-occupying lesions that clinically resemble chronic otitis media.

METHODS

We present a case of bilateral IMTs with facial nerve involvement, sigmoid sinus thrombosis, leptomeningeal enhancement, and seizures.

RESULTS/CONCLUSION

This case demonstrates the need for a high index of suspicion of IMT when imaging reveals bilateral mastoid opacification. These tumors are more aggressive than their orbital counterparts and require multimodality therapy to prevent recurrence and alleviate severe neurotologic symptoms.

Paraplegia in a Patient With IgG4-Related Sclerosing Disease: A Case Report

Immunoglobulin G4 (IgG4)-related sclerosing disease is a systemic disease, characterized by mass forming inflammatory lesions which respond well to steroid therapy. Pancreas is the most common site of involvement, and other organ involvements are also common. However, there are only a few reports about central nervous system involvement. We report a case of IgG4-related sclerosing disease which involves spinal cord causing paraplegia. A middle-aged female presented with sudden lower limb weakness. Magnetic resonance imaging showed a soft tissue mass which was diffusely compressing spinal cord along the C7 to T5 levels. Intravenous steroid pulse therapy and emergent operation was performed. The immunopathologic findings revealed IgG4-related sclerosing pachymeningitis postoperatively. There was no evidence of other organ involvement. Her neurologic deficit remained unchanged after two months of comprehensive rehabilitation therapy.

Plasma cell granuloma of the oral cavity: a mucosal manifestation of immunoglobulin G4-related disease or a mimic?

The aim of the study was to test the hypothesis that oral plasma cell granuloma may represent a mucosal manifestation of immunoglobulin (Ig)G4-related disease (IgG4-RD) in the oral cavity. The study sample comprised two males and four females, aged 54-79 years (median 62 years). The lesions were localized on gingival/alveolar mucosa (four cases), hard palate, and floor of the mouth, measuring 17-40 mm (median 31 mm). The duration of the lesions ranged from 3 months to several years. Information on IgG4 serum levels was available for two patients, and these were increased to 1.85 and 1.65 g/L, respectively. The follow-up period ranged 11-30 months (median 13 months). None of the lesions recurred, and none of the patients developed any manifestation of IgG4-RD. Microscopically, all cases presented as nodular lesions composed of numerous polyclonal plasma cells admixed with lymphocytes, histiocytes, mast cells, and eosinophils, set within collagenized stroma in variable proportions. Obliterative phlebitis was observed in two cases. The number of IgG4-positive plasma cells ranged between 51 and 142 per HPF (median 114), while the IgG4/IgG ratio values ranged between 0.16 and 0.72 (median 0.44) and were above 0.40 in three cases. Based on international criteria, two cases were diagnosed as definite and one as probable IgG4-RD. Oral plasma cell granuloma is a heterogeneous group of lesions, and a subset may represent a mucosal manifestation of IgG4-RD in the oral cavity.

Metaplastic breast carcinoma development following surgical resection of an inflammatory myofibroblastic tumor in the right breast: A case report

Inflammatory myofibroblastic tumors (IMTs) are uncommon, mesenchymal lesions, and malignant transformation is extremely rare. The current study presents the case of a 56-year-old female with a rapidly growing mass in the right breast, which was diagnosed as IMT. Immunohistochemically, the mass was positive for smooth muscle actin (SMA) and Ki-67 (positive staining in 30% of the cells), and negative for S-100, cluster of differentiation (CD)34, p63 and cytokeratin. Malignant transformation to metaplastic carcinoma of the spindle-cell type was observed following surgical resection. This metaplastic carcinoma demonstrated positive immunoreactivity for cytokeratin, vimentin, CD34, p63 and Ki-67 (>30%), and was negative for cytokeratin 7, SMA, desmin and S-100. The patient underwent total mastectomy of the right breast, followed by palliative chemotherapy with capecitabine; however, the patient succumbed to the disease after 12 weeks. The unusual case presented in the current study emphasizes the importance of pre-operative examinations to determine the benign or malignant nature of IMTs, which aids in the choice of appropriate surgical procedures.

Sigmoid sinus occlusion infiltrated by inflammatory myofibroblastic tumor from mastoid

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) and some types of immunoglobulin (Ig) G4-related disease are often involved in the spectrum of inflammatory pseudotumor (IPT) and the concept of IgG4-related IPT/IMT has recently been proposed.

METHODS

A 38-year-old man complained of initial symptoms of blurred vision and headache.

RESULTS

A tumor was found in the right mastoid, which caused occlusion of the right sigmoid sinus and intracranial hypertension. A diagnosis of IMT with IgG4+ plasma cell infiltration was established by surgical, pathological, and immunohistochemistry findings. His symptoms were completely relieved after corticosteroid therapy and no recurrence was detected during 22 months of follow-up.

CONCLUSION

A case with cerebral venous sinus infiltrated by IMTs in the head and neck has never been reported; corticosteroid therapy proved satisfactory in IMT with IgG4+ plasma cell infiltration.

Recurrent laryngeal inflammatory myofibroblastic tumor with positive anaplastic lymphoma kinase mimicking recurrent respiratory papillomatosis: a case report

Inflammatory myofibroblastic tumor (IMT) of the larynx is an unusual lesion, particularly in the pediatric age group. Laryngeal IMTs in children follow a benign clinical course with reports of only rare recurrences and no metastases. Although anaplastic lymphoma kinase (ALK) has been associated with IMTs, there is only one pediatric laryngeal IMT reported to be ALK-positive with immunohistochemical staining. Here, we present a case of a 10-year-old boy with a laryngeal IMT that recurred four times and was misdiagnosed as recurrent respiratory papillomatosis after the initial three operations. ALK positivity was demonstrated by both immunohistochemical staining and fluorescence in situ hybridization. To the best of our knowledge, this case report is the first to describe a laryngeal IMT that recurred multiple times and was confirmed to be ALK-positive at the molecular level.

Pulmonary inflammatory myofibroblastic tumor and IgG4-related inflammatory pseudotumor: a diagnostic dilemma

IgG4-related inflammatory pseudotumor (IPT) and inflammatory myofibroblastic tumor (IMT) share morphological features like a prominent fibroblastic/myofibroblastic proliferation and the presence of inflammatory cells. Since IPT is managed conservatively and IMT is treated by surgical excision, it is important to differentiate these two lesions. The aim of this study is to highlight morphological and immunohistochemical features that distinguish IPT and IMT. Clinicopathological characteristics of cases diagnosed as pulmonary IPT or IMT from 1997 to 2013 were reviewed. The histological features were studied on hematoxylin and eosin-stained sections. Immunohistochemistry was done for IgG, IgG4, ALK-1, SMA, desmin, and CD34 for classification into IPT and IMT. Of the ten patients, seven were male and the age ranged from 4 to 58 years. The tumor size ranged from 1.5 to 4.0 cm in diameter. Histologically, proliferation of bland-looking spindle cells along with fibrosis and an inflammatory infiltrate comprising of lymphocytes and plasma cells were the common morphological features of both lesions. The spindle cell proliferation was more marked in IMT whereas lymphoplasmacytic infiltrate was more prominent in IPT. Obstructive phlebitis was observed only in cases of IPT. IgG4 expression was noted in IPT, and the number of IgG4-positive plasma cells and the ratio of IgG4+/IgG+ plasma cells were significantly lower in IMT than in IgG4-related IPT. Expression of anaplastic lymphoma kinase (ALK) was observed only in IMT, but not in IgG4-related IPT. The proportion of proliferating spindle cells, lymphoplasmacytic infiltrate, obstructive phlebitis, IgG4+ plasma cells and the ratio of IgG4+/IgG+ plasma cells, and ALK expression are helpful in differentiating these morphologically similar but biologically different lesions, which require different treatment modalities.

ALK-1 positive orbital inflammatory myofibroblastic tumour (IMT) associated with prominent numbers of IgG4 plasma cells - a case report

A 14-year-old boy presented with a 2-year history of a supraorbital mass, associated with loss of vision and phthisis. A lack of response to systemic steroids led to an incisional biopsy. This showed a spindle cell lesion with a prominent inflammatory component, with numerous plasma cells. The spindle cells were positive for anaplastic lymphoma kinase (ALK-1). Over 90% of the plasma cells were surprisingly positive for IgG4. The presence of ALK-1 positivity within the spindle cells, coupled with the prominent inflammation indicated a diagnosis of ALK-1 positive inflammatory myofibroblastic tumour (IMT-the neoplastic member of the so called inflammatory pseudotumours). However, the level of IgG4 positivity within the plasma cell population would have otherwise lead to a diagnosis of IgG4 related disease, if the ALK-1 positive spindle cells population was not represented. Recent literature from systemic IMT has alluded to the presence of IgG4 plasma cell positivity in IMT and argues that in the absence of other supporting histological features of IgG4 disease (phlebitis and lymphoid aggregates), as in this case, the presence of IgG4 plasma cells, even in high numbers should not lead to a kneejerk diagnosis of co-existing IgG4 disease. This case report is the first to make this association in the orbit and argues that in the presence of IMT, the IgG4 plasma cells are not necessarily pathogenic.