Inflammatory myofibroblastic tumor in children: clinical review with anaplastic lymphoma kinase, Epstein-Barr virus, and human herpesvirus 8 detection analysis

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.

Inflammatory myofibroblastic tumor of the heart in an older woman with paroxysmal atrial fibrillation: a case report and review of the literature

Inflammatory myofibroblastic tumors (IMTs) of the heart are rarely observed in the eldly. We report a case involving an elderly woman with an IMT situated on the right atrial wall. The tumor was fully excised. The patient had a smooth recovery post-surgery and remained free of recurrence for three years.

Hepatic Inflammatory Pseudotumor-Focusing on Its Heterogeneity

Hepatic inflammatory pseudotumors (IPTs) are defined as benign, non-malignant, non-metastasizing tumors characterized by the presence of myofibroblastic spindle cells, hetorogenous populations of inflammatory cells, particularly plasma cells, lymphocytes and macrophages, as well as locations of fibrosis and necrosis without cellular anaplasia or atypical mitoses. Despite subsequent reports in the references, hepatic IPT remains difficult to diagnose; while posing major issues specifically for its differential diagnosis compared with that of other various benign diseases and malignant hepatic tumors. Histopathological findings are always a requisite for confirming the diagnosis, particularly given that the pathogenesis of IPT remains ambiguous to date. Hepatic IPT is a heterogeneous entity in terms of its clinical features, pathological findings, and pathogenesis. Once the diagnosis is confirmed, however, needless surgery such as wedge resection and lobectomy should be avoided. Here, we discuss the heterogeneity of hepatic IPT, its clinical features, pathological findings, and pathogenesis, and describe its differential diagnosis.

Inflammatory myofibroblastic tumor of the lung involving the central nervous system in pediatric patients

INTRODUCTION

The inflammatory myofibroblastic tumor (IMT) is a very rare lesion with an incidence of less than 0.1% of total neoplasms and with main affection in the lungs. Involvement in the central nervous system is extremely rare, but with a much more aggressive course than IMT diagnosed in the rest of the body. We report the 2 cases presented in our neurosurgery department to date; both were treated satisfactorily without intercurrences in 10 years of follow-up.

HISTORICAL BACKGROUND

The World Health Organization described the IMT as a distinctive lesion composed of myofibroblastic spindle cells accompanied by an inflammatory infiltrate of plasma cells, lymphocytes, and eosinophils.

CLINICAL PRESENTATION

Clinical manifestations of patients with CNS IMT vary and may consist of headache, vomiting, seizures, and blindness. Seizures are the most common symptom in patients with focal lesions.

DIAGNOSIS

The true origin of this entity remains to be elucidated, but to date, etiologies ranging from chromosomal alterations to autoimmune or postinfectious mechanisms have been described. Due to its rarity and non-specificity in imaging, the final diagnosis of IMT in the brain parenchyma relies on pathological examination.

MANAGEMENT

Treatment options are controversial and include total or subtotal removal, high-dose steroids, and radiation therapy. In the last decade, the development of ALK Tyrosine Kinase Inhibitors allows the possibility of chemotherapy in those patients harboring ALK mutations.

CONCLUSION

IMT is a rare tumor that can exceptionally be found in the CNS. The cause is still unknown although the different studies focus on a neoplastic origin. The diagnosis is based in the use of different modalities of imaging and with histological confirmation. Optimal management is gross total resection whenever possible, is the only established curative treatment. Further research with longer follow-up is needed to clarify the natural history of this rare tumor.

Treatment modalities of ALK-positive relapsed/refractory inflammatory myofibroblastic tumor of the brain and lungs in 7-year-old girl: case-based reviews

PURPOSE

Inflammatory myofibroblastic tumor (IMT) belongs to mesenchymal neoplasm of intermediate malignancy in WHO classification. Primary CNS disease or CNS metastases (CNS-IMT) occur in minority. We describe a case of relapsed/refractory IMT of lungs with multiple brain metastases in young child who achieved long-term complete response after alectinib. This systematic review also summarizes treatment modalities and outcome of children and adolescent with CNS-IMT.

METHODS

PRISMA 2020 guideline was applied to select an article from PubMed, Scopus, and Cochrane databases without time limits. This review focused on children and adolescent 0-24 years of age with CNS-IMT or inflammatory pseudotumor (CNS-IPT). The clinical characteristics and treatment outcome were explored.

RESULTS

A total of 51 patients in 49 publications were identified. Median age of patients with CNS-IMT/IPT was 15-year-old and 60.8% were male. The most common location of tumor was cerebral cortex (54.9%). Complete resection of CNS-IMT/IPT was performed in 27 cases with 100% complete response and 18.5% recurrence. Nearly half of patients who received partial resection without adjuvant therapy experienced progressive disease, while the contrast group totally achieved partial response. Overall responses in 7 patients treating with ALK inhibitors were 57.1% durable complete response and 42.9% transient partial response.

CONCLUSION

First-line treatment of CNS-IMT/IPT is complete resection. Patients who received partial tumor removal might have benefit from adjuvant therapy. ALK inhibitors reveal a promising result in unresectable CNS-IMT/IPT. Our case has shown a success in treating relapsed and refractory CNS-IMT as well as the primary site using 2nd-generation ALK inhibitor.

Anaplastic lymphoma kinase inhibitor therapy in the treatment of inflammatory myofibroblastic tumors in pediatric patients: Case reports and literature review

BACKGROUND

Inflammatory myofibroblastic tumors (IMTs) are a rare subtype of inflammatory pseudotumor frequently associated with rearrangement of the anaplastic lymphoma kinase (ALK) gene. Their treatment has historically relied on at-times challenging and morbid surgical excision. Recent studies have shown that neo/adjuvant therapy with ALK inhibitors can significantly enhance outcomes in select patients.

METHODS

A systematic literature review was performed to characterize comprehensive treatment of ALK-positive IMTs in the pediatric population. This report also includes two patients from our home institutions not previously reported in the literature.

RESULTS

We identified a total of 27 patients in 12 studies in addition to 2 patients from the senior authors' institution for a total of 29 patients (median age, 7 years; 52% male). The IMTs comprised a wide range of anatomic locations. Almost half (12, 41.3%) were treated with ALK-inhibitors alone and felt to be in remission. The remainder was treated with ALK-inhibitors either before or after surgery and had a curative response.

CONCLUSIONS

ALK-positive IMTs can be successfully treated with ALK-inhibition alone or in combination with surgical resection. Further genetic characterization may be helpful in determining more precise treatment and defining needed durations thereof.

Clinical characteristics and prognosis of pulmonary inflammatory myofibroblastic tumor: An over 10-year retrospective analysis

Importance

Pulmonary inflammatory myofibroblastic tumors (PIMTs) are primary lung tumors in children. Misdiagnosis easily occurs because of the nonspecific clinical manifestations, laboratory examination results, and imaging findings in affected patients.

Objective

To summarize the clinical characteristics, diagnosis, and prognosis of children with PIMTs.

Methods

This retrospective analysis included 23 children with PIMTs who received treatment in our hospital from January 2008 to January 2019. The clinical manifestations, laboratory examination results, and computed tomography findings were retrospectively analyzed.

Results

The population included 13 boys and 10 girls, with a median age at onset of 78 months (range, 10–126 months). Fourteen patients had PIMT lesions in the right lung and nine patients had PIMT lesions in the left lung. The surgical procedures included pulmonary wedge resection, pulmonary lobectomy, and total pneumonectomy. The median operation time was 115 min (range, 45–235 min); the median intraoperative blood loss volume was 30 mL (range, 3–500 mL). During the operation, one patient each had pulmonary hemorrhage, vena cava hemorrhage, and thoracic duct injury. Postoperative complications included pulmonary embolism in one patient and tumor recurrence in two patients; neither of these complications recurred after reoperation. The median follow‐up period was 49 months (range, 2–127 months).

Interpretation

Children with PIMTs exhibited good prognoses and primarily underwent surgical resection as treatment. Complete preoperative evaluation should be performed in affected patients.

Anaplastic lymphoma receptor tyrosine kinase-negative inflammatory myofibroblastic tumor of triceps brachii: Case report

Inflammatory myofibroblastic tumor (IMT) is a non-neoplastic benign lesion comprising various inflammatory cells, including myofibroblasts and vascular tissues. It is a rare tumor that sometimes shows similar signs and progression as malignant tumors. The anatomical sites of IMTs include the lungs, liver, orbit, skin, mesentery, and maxillary sinus, but they rarely occur in the limb musculoskeletal system. To our knowledge, no case of neurological symptoms caused by the tumor in the triceps brachii muscle has been reported. In this article, we report the case of a 42-year-old male patient with an IMT that grew rapidly in the triceps brachii muscle and consequently caused symptoms of ulnar nerve lesion owing to its increasing size. The patient showed no ulnar nerve lesion symptoms after undergoing wide excision and was diagnosed with anaplastic lymphoma receptor tyrosine kinase- negative IMT.

TERT promoter mutation analysis as a surrogate to morphology and immunohistochemistry in problematic spindle cell lesions of the urinary bladder

AIMS

Pseudosarcomatous myofibroblastic proliferations (PSMPs) of the urinary bladder are diagnostically challenging. Diagnostic difficulties are mainly due to frequent cytokeratin expression, variable ALK expression and worrisome morphological features suggestive of malignancy. Conversely, sarcomatoid urothelial carcinoma (UC) may show bland inflammatory myofibroblastic tumour (IMT)-like morphology. TERT promoter mutations are characteristic events in urothelial cancers, but have not been studied in PSMPs.

METHODS AND RESULTS

We compared histomorphological and immunohistochemical features and TERT promoter status in 16 PSMPs and 18 sarcomatoid UC. In a subset of PSMPs, RNA sequencing was performed. At least focal IMT-like morphology was seen in nine of 17 sarcomatoid UC. Atypical mitoses, differentiated urothelial component and heterologous elements were the most reliable distinguishing histomorphological features of sarcomatoid UC, if present. A panel of immunohistochemistry (IHC) including ALK (clone D5F3), p53 pattern, p63 and GATA3 reliably distinguished PSMP from sarcomatoid UC. GATA3 (P = 0.001) and p53 patterns (mutant versus wild-type; P < 0.001) were differentially expressed between PSMPs and sarcomatoid UC. Diffuse pancytokeratin staining was significantly associated with PSMPs (10 of 13) compared to four of 14 sarcomatoid UCs (P = 0.012). TERT promoter mutations were found in 17 of 18 sarcomatoid UC versus none of 16 PSMPs (P < 0.001). RNA sequencing revealed ALK genetic rearrangements in one of two ALK-positive and one of 10 ALK-negative PSMPs, which revealed a novel FN1/RET gene fusion.

CONCLUSION

Careful histomorphological analysis and differential IHC reliably distinguish the majority of PSMPs and sarcomatoid UC. In equivocal cases, TERT promoter mutation analysis and/or detection of ALK expression/rearrangements are valuable additional diagnostic adjuncts, strongly supporting sarcomatoid UC and PSMP, respectively.

Inflammatory Myofibroblastic Tumor of the Urinary Bladder and Ureter in Children: Experience of a Tertiary Referral Center

PURPOSE

To present the clinicopathological characteristics and outcome of children with bladder and ureteral inflammatory myofibroblastic tumors (IMTs) in our center.

METHODS

We reviewed the medical records of patients with bladder and ureteral IMTs from 2010 to 2018. We recorded patients' demographic data, presentation, hemoglobin level, presence of hydronephrosis, tumor size, treatment, and outcomes.

RESULTS

Eight patients with bladder IMTs and 3 with ureteral IMTs were treated at our center during this period. The mean age was 7.1 years. Four patients presented with anemia at diagnosis with the mean hemoglobin level 84.5 g/L. Among patients with bladder IMTs, 5 were male and 3 were female. The most common symptom was lower urinary symptoms in 6 patients, followed by hematuria in 4 patients. 2 patients had complications of hydronephrosis and hydroureter. Among patients with ureteral IMTs, 2 were male and one was female. The most common symptom was abdominal pain, and 3 patients presented with upper urinary tract dilation. All patients underwent surgery. A total of 81.8% were positive for anaplastic lymphoma kinase. Cytokeratin (CK) expression was present in all patients with bladder IMTs, while it was negative in 2 patients with ureteral IMTs. During mean follow-up of 43.4 months, all patients survived event-free.

CONCLUSION

The presence of hydronephrosis and hydroureter is rare in patients with bladder IMTs. Anemia caused by hematuria should be raised the index of suspicion for IMTs. Children with bladder and ureteral IMTs had excellent prognosis. The expression pattern of CK varied between bladder and ureteral IMTs.

Pediatric thoracic mass lesions: Beyond the common

Thoracic mass lesions can be categorized as originating in one of the three major compartments: a) chest wall and pleura, b) lung parenchyma and airways, c) mediastinum. While some of these, such as lymphoma, are common in both children and adults, others are rare and unique to childhood. The goal of this review is to familiarize radiologists with unusual but distinctive mass lesions of the pediatric thorax.

Spontaneous pneumothorax caused by an inflammatory myofibroblastic tumor-like lesion in a 14-year-old girl: a case report

Background

Spontaneous pneumothorax occurs more often in younger, slim, and shallow-chested men. Although less common, differential diagnoses for secondary pneumothorax in children are asthma, emphysematous blebs, catamenial pneumothorax, and others. We report a patient who presented with pneumothorax and was found to have an inflammatory myofibroblastic tumor (IMT)-like lesion, and present a review of the related literature.

Case presentation

A 14-year-old girl visited her physician for chest pain that developed while exercising. Although chest drainage was performed, the symptoms associated with a collapsed lung did not improve, and she was referred to our hospital. Computed tomography revealed the presence of a 19 × 17-mm cyst with a thick wall in the apex of the right lung. She was tested for infectious diseases, namely tuberculosis, but the results were not definitive. Catamenial pneumothorax was also suspected because she was menstruating when she presented to our hospital. As a therapeutic diagnosis, we performed a thoracoscopic partial resection of the right upper lobe of the lung. Three small openings were identified inside the cyst, suggesting connection with the bronchiole. The lesion was pathologically diagnosed as an IMT-like lesion. Considering the progress so far, we considered that the final diagnosis to be an IMT. The patient was discharged on postoperative day 3, and we have followed her for the past 6 months with no local recurrence or metastasis.

Conclusions

IMT is not uncommon in children. Therefore, this lesion should be considered as a possible diagnosis if children and young adults develop spontaneous pneumothorax.

Prolapsing inflammatory myofibroblastic tumor of the urinary bladder: A case report and a review of literature

Inflammatory myofibroblastic tumor (IMT) of the urinary bladder is a rare soft tissue benign tumor usually presents with hematuria, dysuria or obstructive urinary symptoms. No distant metastasis has been reported except in a single case. There is no clear consensus on the management plan yet. However, complete surgical resection is the mainstay management. We reported a case of a female patient presented with a painless prolapsing urethral mass that bleeds of touch with no signs of local invasion or distant metastasis, complete resection and pathological evaluation of the specimen revealed an IMT. The postoperative period was uneventful for 1 year.

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.

Anaplastic Kaposi's Sarcoma of the Adrenal in an HIV-negative Patient With Literature Review

Kaposi's sarcoma (KS) is a peculiar tumor of viral etiology, with the HHV8 rhadinovirus playing a fundamental role in its development. Several epidemiological categories of KS have been identified, of which the sporadic, endemic, iatrogenic, and the epidemic are the main ones. Several histologic disease morphologies have been described, such as inflammatory, angiomatous, spindle cell, mixed, and the anaplastic (sarcomatous) subtypes. The skin of the limbs is most commonly affected, but any other organ or site may be involved. Microscopically KS may enter the differential diagnosis with several different entities, and for this purpose the immunohistochemical detection of the viral latent nuclear antigen-1 (LNA-1) may be crucial. Sporadic KS is usually benign, but rarely it may be aggressive. Anaplastic histology heralds an ominous course in any clinical context. We report a case of anaplastic retroperitoneal KS, occurring in an HIV-negative adult man. This patient presented with a huge left suprarenal mass, which was totally resected, and initially diagnosed as inflammatory leiomyosarcoma, because of the monomorphic spindle cell tumor morphology. After 12 years the tumor recurred locally as an unresectable mass, which was biopsied and examined. At the time of recurrence, the histologic slides of the primary tumor were reviewed, and the previous diagnosis was changed to that of atypical KS. Histologically the recurrent tumor showed both spindle cell and epithelioid appearances. Strongly diffuse HHV8/LAN-1 immunopositivity was documented in both tumors. The final diagnosis for the entire case was anaplastic KS. Then, the patient died in a few months.

Ultrasonic Manifestations of Mesenteric Inflammatory Myofibroblastic Tumors in Children

Objective: To explore the ultrasonic manifestations of mesenteric inflammatory myofibroblastic tumors (IMTs) in children. Methods: Seven patients with mesenteric IMTs were retrospectively analyzed. The ultrasonic manifestations, such as the locations, sizes, morphology, borders, internal echo, blood flow, and metastasis, of the tumors were detected. Results: In all the seven pediatric patients, a solitary lesion was found for the mesenteric IMTs, including five cases in the ileocecal mesentery and two cases in the mesentery of ascending colon. All the single tumors were revealed as irregular hypoechoic masses with uneven internal echoes and enhanced echoes in the surrounding intestine and omentum. Internal blood flow signals were enriched in the tumors. The borders were clear in five cases and unclear in two cases. In addition, two cases had peritoneal effusion and one case had calcified plaques. In the follow-up studies, one of the seven IMT patients had malignant transformation, and one case was transferred to the pelvic cavity. Conclusion: Ultrasonic examination can clearly demonstrate the locations, sizes, morphology, borders, internal echo, blood flow as well as metastasis of the pediatric IMT of the mesentery, having an important clinical application value as an adjunct to computed tomography (CT).

Ureteral inflammatory myofibroblastic tumor: A case report and literature review

RATIONALE

Inflammatory myofibroblastic tumor (IMT) is a rare soft-tissue neoplasm which has been described in a variety of locations. In the urogenital system, IMT predominantly occurs in the bladder and the kidney. IMT arising from the ureter is exceedingly rare and has been sporadically reported before.

PATIENT CONCERNS

We reported an extremely exceptional case of IMT arising from the ureteral submucosa in a 54-year-old man. The patient was hospitalized with the main complaint of intermittent and moderate left abdominal pain for 2 months.

DIAGNOSES AND INTERVENTIONS

Computed tomography scan revealed a nearly circular mass in the left upper ureter. Ureteroscopy showed that the ureteral lumen mucosa was smooth. However, the upper ureter was compressed and narrow. Renal dynamic imaging was performed and the measured glomerular filtration rate was 46.98 mL/min (right renal) and 9.77 mL/min (left renal), respectively. A retroperitoneoscopic radical nephroureterectomy was performed. The histopathologic examination revealed that the soft-tissue neoplasm was mainly composed of myofibroblastic spindle cells proliferation with mixed inflammatory infiltrate, containing lymphocytes, neutrophils, and eosinophils. On immunohistochemical staining, the tumor was positive for smooth muscle actin and Ki-67 (<1%+), indicating a confirmed diagnosis of ureteral IMT.

OUTCOMES

The patient recovered well with no occurrence of complications. At 3-year follow-up, there was no radiologic evidence of tumor recurrence or metastasis and the man was well.

LESSONS

Ureteral IMT is extremely rare and often asymptomatic, resulting in delayed diagnosis. Radiologic evidences may be suggestive of the diagnosis of IMT. However, it is necessary to make an accurate diagnosis in terms of histopathologic assessment. Complete lesion excision is the best therapeutic approach with rare recurrences and excellent survival.

Computed Tomography and Magnetic Resonance Imaging Findings of Inflammatory Pseudotumors in the Abdomen and Pelvis: Current Concepts and Pictorial Review

The group of inflammatory pseudotumors (IPTs) encompasses a variety of rare neoplastic and nonneoplastic entities described to occur in almost every location in the body and whose clinical features and aggressive imaging findings (varying from infiltrative to mass-forming lesions), frequently mimic those of malignant tumors. The radiologic features of IPTs are variable and nonspecific, the imaging findings depending on the body location and involved organ. Abdominopelvic IPTs are rare and the purposes of this review, therefore, are to familiarize the radiologist with the wide spectrum of computed tomography and magnetic resonance imaging findings of IPTs in various locations throughout the abdomen and pelvis, discussing the imaging features that allow consideration of IPTs in the differential diagnosis of soft-tissue masses within the pertinent clinical setting. Radiologists should be aware of this group of entities, as a preoperative histopathologic diagnosis upon radiological suspicion may help to differentiate IPTs from malignancy and to allow the most appropriate clinical work-up for these patients.

Relapsed and unresectable inflammatory myofibroblastic tumor responded to chemotherapy: A case report and review of the literature

A 63-year-old female patient who had undergone cholecystectomy for inflammatory myofibroblastic tumor (IMT) in the gallbladder was referred to our hospital. The patient's disease relapsed, involving the pancreas, and was diagnosed as inoperable IMT 13 months after the cholecystectomy. The patient failed to respond to steroid and non-steroidal anti-inflammatory drug therapy, but subsequently exhibited a good response to vinorelbine and methotrexate combination chemotherapy. Little information is currently available on the efficacy of chemotherapy for adult-onset IMT. The present case suggests that chemotherapy with vinorelbine and methotrexate is a viable therapeutic option for adult patients with unresectable IMT.

Inflammatory myofibroblastic tumors of the lung carrying a chimeric A2M-ALK gene: report of 2 infantile cases and review of the differential diagnosis of infantile pulmonary lesions

We report 2 infantile cases of pulmonary tumor carrying a chimeric A2M-ALK gene. A2M-ALK is a newly identified anaplastic lymphoma kinase (ALK)-related chimeric gene from a tumor diagnosed as fetal lung interstitial tumor (FLIT). FLIT is a recently recognized infantile pulmonary lesion defined as a mass-like lesion that morphologically resembles the fetal lung. Grossly, FLIT characteristically appears as a well-circumscribed spongy mass, whereas the tumors in these patients were solid and firm. Histologically, the tumors showed intrapulmonary lesions composed of densely proliferating polygonal or spindle-shaped mesenchymal cells with diffuse and dense infiltrations of inflammatory cells forming microcystic or micropapillary structures lined by thyroid transcription factor 1-positive pneumocytes, favoring inflammatory myofibroblastic tumor rather than FLIT. The proliferating cells were immunoreactive for ALK, and A2M-ALK was identified in both tumors with reverse-transcription polymerase chain reaction. The dense infiltration of inflammatory cells, immunoreactivity for ALK, and identification of an ALK-related chimeric gene suggested a diagnosis of inflammatory myofibroblastic tumor. Histologically, most reported FLITs show sparse inflammatory infiltrates and a relatively low density of interstitial cells in the septa, although prominent infiltration of inflammatory cells and high cellularity of interstitial cells are seen in some FLITs. The present cases suggest that ALK rearrangements, including the chimeric A2M-ALK gene, may be present in these infantile pulmonary lesions, especially those with inflammatory cell infiltration. We propose that these infantile pulmonary lesions containing a chimeric A2M-ALK gene be categorized as a specific type of inflammatory myofibroblastic tumor that develops exclusively in neonates and infants.

ALKG1269A mutation as a potential mechanism of acquired resistance to crizotinib in an ALK-rearranged inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumors are rare mesenchymal neoplasms frequently harboring oncogenic chromosomal rearrangements, most commonly, involving the ALK (anaplastic lymphoma kinase) gene. Treatment of this molecularly defined subgroup with the anaplastic lymphoma kinase inhibitor crizotinib has shown to be effective. However, comparable to lung adenocarcinoma, resistance inevitably develops. Second generation anaplastic lymphoma kinase inhibitors such as ceritinib are able to overcome acquired resistance to crizotinib. Here, we report the case of a patient with an inflammatory myofibroblastic tumors harboring a DCTN1-ALK fusion who developed resistance to crizotinib treatment. Next-generation sequencing of a rebiopsy sample revealed the acquisition of the ALK^G1269A mutation as a mechanism of resistance. Therapy with ceritinib resulted in a short but profound clinical, metabolic and morphologic response. This case illustrates that (i) different tumor entities may share similar oncogenic driver mechanisms, rendering them vulnerable for the same therapeutic substances and (ii) likewise, the same mode of resistance may occur under targeted therapy among different tumor entities.

Inflammatory Myofibroblastic Tumor of the Heart in the Infant: Review of the Literature

Primary heart tumors are extremely rare, constituting approximately 0.02% of all malignancies. Inflammatory myofibroblastic tumor (IMT) constitutes <5% of primary heart tumors. Until now, IMT of the heart has been described in 21 infants below 1 year of age. Its etiology remains unknown. IMT usually develops within the right atrial and ventricular endocardium. The main clinical symptoms reported in the affected infants involved increasing respiratory failure, cyanosis, and heart murmurs. Histopathologically, IMT is characterized by the myofibroblast proliferation with inflammatory infiltrates composed of plasmocytes, lymphocytes, and histiocytes. Tumor resection is the treatment of choice in IMT. Such tumor location is associated with the high risk of perioperative failure. Steroid therapy and chemotherapy is reported in the literature as a nonsurgical treatment alternative. Here, we present a review of clinical symptoms, diagnostic and treatment options, based on published case reports of IMT in infants, including our 11-month-old patient with IMT located within the pericardium.

[Intestinal intussusception secondary to myofibroblastic tumor in an elderly patient. Case report]

BACKGROUND

Intussusception is defined as a segment of the gastrointestinal tract and mesentery within the lumen of an adjacent segment. It is a rare condition in adults that can occur anywhere in the gastrointestinal tract from the stomach to the rectum. Only 5% of all intussusceptions are presented in adults, and in 1-5% of all cases of intestinal obstruction. Inflammatory myofibroblastic tumour is rare, and is usually found in the lung, and rarely detected in some intestinal portions. It causes a variety of non-specific symptoms, with those that present as an intussusception being uncommon.

CLINICAL CASE

A female of 69 years with partial bowel obstruction secondary to intestinal intussusception due to an inflammatory myofibroblastic tumour, a rarely diagnosed condition and never published before.

DISCUSSION

Inflammatory myofibroblastic tumours are rare, and in this case with an atypical presentation that was surgically resolved satisfactorily. These entities are difficult to diagnose, with histopathology giving the definitive diagnosis. A literature review was performed to gather recent information about their diagnosis and treatment.

CONCLUSIONS

Inflammatory myofibroblastic tumours require a high level of suspicion, as diagnosis prior to surgery is difficult. Surgery is considered the treatment of choice, requiring leaving free surgical edges to prevent recurrences.

Inflammatory pseudotumor (IPT)-surgical cure of an inflammatory syndrome

We report on four female adolescents, who presented with inflammatory symptoms. Extensive diagnostic workup revealed tumors on different locations. After surgical removal, clinical and laboratory signs of inflammation disappeared rapidly. On histology, the tumors showed a mixture of inflammatory cells characteristic of inflammatory pseudotumors in three of the patients.

CONCLUSION

In patients with unclear inflammatory symptoms, inflammatory pseudotumor should be added to the differential diagnosis.

WHAT IS KNOWN

• The inflammatory pseudotumor (IPT) is a mostly benign myofibroblastic tumor of the soft tissue and causes inflammatory symptoms. What is new: • IPTs have may wider than hitherto defined histologic features. Removal of IPT is curative.

[Complete resolution of inflammatory myofibroblastic tumor of the bladder after antibiotic therapy]

Inflammatory myofibroblastic tumors (IMT) are rare benign tumors, most commonly arising in the lungs and urinary bladder. Many etiologic factors are suspected in their development, but none have been formally demonstrated. Conventional treatment for bladder IMT is complete surgical resection by partial cystectomy or transurethral resection. We report the case of an 8-year-old girl with documented bladder IMT that resolved completely after antibiotic therapy.

[Contribution of radio-guided biopsy in the histopathological diagnosis of childhood tumors of: experience of Rabat Child Hospital]

La biopsie radioguidée constitue une alternative à la biopsie chirurgicale invasive et à la cytologie pour le diagnostic des tumeurs pédiatriques. L'intérêt de notre étude est d’évaluer la valeur diagnostique des biopsies radioguidées examinées au laboratoire d'anatomopathologie de l'hôpital d'Enfants de Rabat (HER). L’étude a porté sur 78 biopsies radioguidées recueillies dans notre laboratoire entre janvier 2008 et décembre 2011. l’âge moyen des patients était de 5 ans et 10 mois avec une prédominance masculine (65,4%). La tumeur était abdominale dans 80% des cas, thoracique dans 15% cas, thoracique et abdominale dans 2,5% et sacrée dans 1,2%. Les biopsies étaient écho-guidées dans 90% des cas et scannoguidées dans 10% des cas. Le diagnostic histopathologique était posé dans 89% des cas. L'immuno-histochimie a été indiquée dans 35% des cas. Les diagnostics les plus fréquents étaient: tumeurs neuroblastiques (42 cas), lymphomes non hodgkiniens (10 cas), rhabdomyosarcomes (6 cas), autres (sarcome d'Ewing, néphroblastomes, tumeur myofibroblastique inflammatoire, maladies de Hodgkin, leucémie aiguë, hépatoblastome et ostéosarcome). Dans notre série, la biopsie radioguidée a permis un diagnostic histopathologique certain dans 89% des cas. Elle nécessite une étroite collaboration entre clinicien, radiologue et anatomopathologiste pour discuter son indication, afin de diminuer le nombre de biopsies peu ou non représentatives.

Shedding light on inflammatory pseudotumor in children: spotlight on inflammatory myofibroblastic tumor

Inflammatory pseudotumor is a generic term used to designate a heterogeneous group of inflammatory mass-forming lesions histologically characterized by myofibroblastic proliferation with chronic inflammatory infiltrate. Inflammatory pseudotumor is multifactorial in etiology and generally benign, but it is often mistaken for malignancy given its aggressive appearance. It can occur throughout the body and is seen in all age groups. Inflammatory pseudotumor has been described in the literature by many organ-specific names, resulting in confusion. Recently within this generic category of inflammatory pseudotumor, inflammatory myofibroblastic tumor has emerged as a distinct entity and is now recognized as a fibroblastic/myofibroblastic neoplasm with intermediate biological potential and occurring mostly in children. We present interesting pediatric cases of inflammatory myofibroblastic tumors given this entity's tendency to occur in children. Familiarity and knowledge of the imaging features of inflammatory pseudotumor can help in making an accurate diagnosis, thereby avoiding unnecessary radical surgery.

Inflammatory myofibroblastic tumour of the bladder in children: a review

INTRODUCTION

Inflammatory myofibroblastic tumours of the bladder (IMTB) are rare, and feature a benign and reactive proliferation of myofibroblasts. 25% of the reported IMTB cases in the literature occur in children. The present study presents a review of IMTB in children.

DISCUSSION

The data from 42 reported cases of paediatric IMTB in the world literature are summarised, including two recent cases from the present centre. Paediatric IMTB equally affects males and females. It mainly presents with haematuria, dysuria or abdominal pain. Lesions can vary in size, but mean size is 5.5 cm. Mean age is 7.5 years. The aetiology of IMTB is poorly understood, but includes infective or traumatic aetiologies, or a possible clonal lesion. IMTB may specifically show clonal gene rearrangements involving the anaplastic lymphoma kinase (ALK-1) gene. To differentiate IMTB from rhabdomyosarcoma, tissue diagnosis and careful histological analysis are essential. Tumour biopsy can be achieved by a transurethral approach or a transcutaneous approach with ultrasound guidance. Between 35 and 89% of cases of IMTB express ALK-1 by immunohistochemistry. ALK-1 expression is much less common in other bladder soft tissue tumours. ALK-1 is thus useful in the diagnosis of IMTB. The treatment of choice for IMTB is complete surgical resection of the lesion. In children, no proven recurrent or metastatic IMTB episodes are reported after excision. However IMTB recurrences are reported in adults, likely due to incomplete excision. Follow-up after excision is therefore recommended.

CONCLUSIONS

Paediatric IMTB is uncommon. Tissue biopsy is essential for diagnosis. Careful histological assessment is required to differentiate IMTB from malignant paediatric bladder tumours such as rhabdomyosarcoma. ALK-1 expression is useful in confirming the diagnosis of IMTB. Treatment of choice is complete surgical resection of the lesion. Recurrence is reported in adult IMTB. Follow-up is therefore recommended.

Primary Inflammatory Myofibroblastic Tumors of the Breast with Metastasis: Radiographic and Histopathologic Predictive Factors

Primary inflammatory myofibroblastic tumors (IMTs) of the breast are uncommon and metastasis of IMTs is extremely rare. To date, the natural course of this disease is not fully understood. Although patients with IMTs should undergo regular follow-up after complete surgical resection of the tumor, the appropriate interval and method of follow-up are unclear. We report the case of a patient with an IMT of the breast that metastasized 2 years after complete surgical resection. This unusual case emphasizes the importance of preoperative examinations to determine whether the IMT has atypical features that should guide the interval and method of follow-up.

Retrospective and comparative study of inflammatory myofibroblastic tumor of the liver

BACKGROUND AND AIM

Inflammatory myofibroblastic tumor of the liver (IMTL) is a very rare benign disease with a good prognosis. The study aims to determine the clinical, radiological, and pathological characteristics of IMTL. The diagnosis and treatment strategies were discussed.

METHODS

A total of 11 patients with pathologically confirmed IMTL receiving treatment over a 15-year period were reviewed retrospectively. The analysis included demographics information and pertinent clinical data. Results obtained from patients with hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (IHCC), and metastatic liver cancer (MLC) receiving surgical resection were compared.

RESULTS

In comparison to HCC, IHCC, and MLC, IMTL has an earlier onset (P < 0.001). IMTL patients had significantly lower aspartate aminotransferase (P = 0.003) and higher alkaline phosphatase (P = 0.034) than HCC patients, and higher gamma-glutamyl transpeptidase (P = 0.010) than MLC patients. Increased serum α-fetoprotein level was detected in only one patient. Serum α-fetoprotein was significantly lower in patients with IMTL (P = 0.000) than in those with HCC but not IHCC (P = 0.558) or MLC (P = 0.514). In contrast to elevated serum CA19-9 in patients with HCC/IHCC/MLC, the serum CA19-9 in IMTL cases was generally normal (vs HCC P = 0.008; vs IHCC P = 0.000; vs MLC P = 0.022). In nine IMTL patients, the tumor appeared as a hypoechogenic solid mass on the ultrasonography. In contrast, most patients with HCC, IHCC, or MLC showed hybrid echo. In contrast computed tomography and magnetic resonance imaging, the lesion of IMTL and MLC appeared as peripheral enhancement.

CONCLUSION

Lab tests, imaging features, and patient history are helpful in the differential diagnosis of IMTL from HCC/IHCC/MLC. Surgical resection is curative for IMTL.

Inflammatory myofibroblastic tumor of the uterus: clinical and pathologic review of 10 cases including a subset with aggressive clinical course

Inflammatory myofibroblastic tumor is currently regarded as a neoplasm with intermediate biological potential and a wide anatomic distribution. Inflammatory myofibroblastic tumors of the female genital tract are rare, and to date reported cases behaved indolently. We describe, herein, 10 cases of uterine inflammatory myofibroblastic tumor, 3 of which had an aggressive clinical course. Subject age ranged from 29 to 73 years. Tumors were composed of spindle and epithelioid myofibroblastic cells admixed with lymphoplasmacytic infiltrates in a variably myxoid stroma. Two growth patterns, myxoid and fascicular (leiomyoma-like), were noted. All tumors were positive for ALK expression by immunohistochemistry, which was stronger in the myxoid areas. Smooth muscle marker and CD10 expression was variable in extent, but typically positive. Fluorescence in situ hybridization for ALK rearrangements was positive in both fascicular and myxoid areas in all 8 cases tested. Three subjects showed clinical evidence of tumor aggressiveness as defined by extrauterine spread, local recurrence, or distant metastasis. Aggressive tumors were larger, had a higher proportion of myxoid stroma, and higher mitotic activity than indolent tumors. Tumor cell necrosis was seen only in cases with adverse outcome. This is the first report to describe aggressive biological behavior in uterine inflammatory myofibroblastic tumor. This diagnosis is often underappreciated and merits inclusion in the differential diagnosis of myxoid mesenchymal lesions of the uterus, particularly because patients with an aggressive course may benefit from targeted therapy.

Inflammatory myofibroblastic tumours of the maxillary sinus: A brief clinical report and review of the literature

Although inflammatory myofibroblastic tumours (IMTs) have been accepted as a clonal neoplasm, their pathology is poorly understood due to variable presentation. There is no identifiable cause and they are usually observed as tumour growth combined with inflammation. In the current WHO classification, IMTs are designated as intermediate malignancies. In terms of biological potential, IMTs are classified under 'rarely metastasizing'. IMTs are rare in the maxillary sinus but, when reported, can be locally aggressive or even destructive if they invade the orbit. The authors present a brief clinical report describing a five-year-old girl with a slow-growing mass in the right maxillary sinus extending into the lacrimal sac and its management.

Inflammatory myofibroblastic tumor: an unusual mimicker of childhood intrathoracic tuberculosis

Inflammatory myofibroblastic tumors are rare lesions of uncertain etiology that are often difficult to diagnose because of their myriad clinical presentations. Not uncommon, they mimic persistent pneumonia. We report a 4-year-old girl who presented with prolonged pyrexia, weight loss, severe anemia, hepatosplenomegaly, and nonresolving pneumonia. Initial investigations including flexible bronchoscopy and bronchial washing for usual causes of persistent pneumonia, such as tuberculosis and other infections, were negative. Chest computed tomography revealed a well-defined lesion involving the lingula and left upper lobe with extension into the subpleural space. Pleural tap and biopsy was also noncontributory. Thoracoscopic biopsy was suggestive of an inflammatory myofibroblastic tumor. As the lesion was encasing the major vessels, it was considered inoperable. The patient did not respond to steroid therapy and etoricoxib and later succumbed to the illness. This uncommon tumor should be considered in the differential diagnosis of children who presented with unresolving consolidation with pyrexia.

Synchronous posttransplant lymphoproliferative disorder and inflammatory myofibroblastic tumor of the lung in a 2-year-old liver transplanted boy: a case report

Inflammatory myofibroblastic tumor is a rare benign lesion found mostly in children and young adults. It originates from the lung, abdominopelvic region, and retroperitoneum. The tumor is composed of myofibroblasts and inflammatory cell infiltration in the tissue. The cause and pathogenesis of this tumor are not completely understood. Epstein-Barr virus has been held responsible in some reported cases of inflammatory myofibroblastic tumors. Another tumor (which is known to be related to the Epstein-Barr virus) is posttransplant lymphoproliferative disorder. We report the case of a 2-year-old boy who underwent a liver transplant at the age of 9 months (the donor was his mother) because of biliary atresia. At 11 months after transplant, we detected posttransplant lymphoproliferative disorder and inflammatory myofibroblastic tumor concurrently. This entity is presented to highlight possible Epstein-Barr virus involvement in inflammatory myofibroblastic tumor of lung.

Inflammatory myofibroblastic tumor of the colon with an unusual presentation of intestinal intussusception

Inflammatory myfibroblastic tumor (IMT), also known as inflammatory pseudotumor is unusual, benign solid tumor. This tumor is commonly reported in the lungs but can be present in extrapulmonary sites as well. We present the case of a 7-year-old girl with IMT in an unusual location. The patient was admitted with abdominal pain, and ultrasound showed a solid mass in the abdomen. She was operated and colocolic intussusception secondary to a mass was found. Histologic evaluation of mass revealed IMT.

Low-grade myofibroblastic proliferations of the urinary bladder

CONTEXT

Myofibroblastic proliferations of the urinary bladder, which share some similarities with nodular fasciitis, were first reported in 1980. Since then, they have had several designations, the most frequently used being inflammatory myofibroblastic tumor. Based on both histopathologic and prognostic grounds, some authors prefer the term pseudosarcomatous myofibroblastic proliferation, at least for some of the proliferations. These same scientists also assimilate the so-called postoperative spindle cell nodules with the pseudosarcomatous myofibroblastic proliferations. Little is known about these low-grade myofibroblastic proliferations.

OBJECTIVES

To review the literature about low-grade myofibroblastic proliferations occurring in the urinary bladder.

DATA SOURCES

Textbooks and literature review. We obtained most of the clinicopathologic peculiarities from a patient population composed of the most-relevant, previously reported cases.

CONCLUSIONS

The low-grade myofibroblastic proliferations of the urinary bladder are rare lesions affecting males more often than they do females. The most-common signs and symptoms are hematuria and dysuria. Histopathologically, they are spindle cell proliferations in a loose myxoid stroma, even though compact proliferations or hypocellular fibrous patterns can be found. Immunohistochemistry is quite nonspecific, except for ALK-1 positivity (20%-89%). Fluorescence in situ hybridization has demonstrated clonal genetic aberrations involving the ALK gene in 50% to 60% of cases. After surgery, only 6% of patients experience local recurrence, without metastases or deaths from the disease. Malignant transformation has been reported exceptionally. These myofibroblastic proliferations are probably part of a continuum with, at one end, benign pseudosarcomatous proliferations and, at the opposite end, more-aggressive lesions. Because of the frequently indolent clinical course, aggressive treatment would be unjustified.

Inflammatory myofibroblastic tumors in childhood

Inflammatory myofibroblastic tumor (IMT) is a rare tumor of intermediate malignant potential that can occur anywhere in the body. Surgical resection is the principal treatment. We report on nine children diagnosed with IMT at our institution over a 10-year period. Presenting symptoms were reflective of tumor location. Complete surgical resection was curative. Local recurrence occurred in the presence of involved surgical margins. One patient with metastatic disease achieved long-term remission with chemotherapy alone. Severe inflammatory response and death occurred in one patient. The 3-year event free and overall survivals (OS) were 58 ± 20% and 89 ± 10% respectively.

Quantification of Epstein-Barr virus DNA in patients with idiopathic orbital inflammatory pseudotumor

Inflammatory pseudotumors (IPT) are soft tissue tumors that include a diverse group of lesions characterized by inflammatory cell infiltration and variable fibrotic responses. Idiopathic orbital inflammatory pseudotumors (IOIP) are IPTs of unknown etiology that develop in the orbit. Due to the lack of well-defined pathogenic mechanisms, diagnosis and treatment of this disease remain a significant challenge. Epstein-Barr virus (EBV) infection, which causes significant lymphocyte infiltration, has been proposed to be involved in IOIP. This study tries to validate the relationship between EBV infection and the development of IOIP. Sixteen IOIP tissue samples were obtained from patients during surgical resection of the lesion. One Graves' ophthalmopathy tissue sample and 20 normal donors' plasma serves as controls. The plasma level of five EBV antibodies, including VCA-IgG, VCA-IgA, VCA-IgM, EA-IgG and EBNA1-IgG were examined. All plasma samples were EB-VCA-IgG positive and EB-VCA-IgM negative, suggesting that all people tested had been infected with EBV but not in the acute infection stage. EBV-DNA was detected in 15/16 (94%) of IOIP tissue samples despite different levels of lymphocyte infiltration and 5/16 plasma samples (31%) were detected EBV DNA positive which is higher than the normal controls (10%). Percent of positive plus suspected positive samples with one or more of the three important risk markers (VCA-IgA, EA-IgG, EBV-DNA) is 50% of the patients (8/16) which is much higher compare with the normal controls (20%). The results further reveal the relationship between IOIP and EBV infection.

Locally invasive pulmonary inflammatory myofibroblastic tumors in children

Two uncommon cases of locally invasive pulmonary inflammatory myofibroblastic tumor are reported. Diagnosis was established by a prior thoracotomy and incisional biopsy. Complete excision was curative and both children remain asymptomatic at last follow up.

A case of inflammatory myofibroblastic tumor originated from the greater omentum in young adult

Inflammatory myofibroblastic (IMF) tumor is a rare solid tumor that often affects children. IMF tumors occur primarily in the lung, but the tumor may affect any organ system with protean manifestations. A 22-year-old woman was evaluated for palpable low abdominal mass that had been increasing in size since two months prior. Abdominal computed tomography showed a lobulated, heterogeneous contrast enhancing soft tissue mass, 6.5 × 5.7 cm in size in the ileal mesentery. At surgery, the mass originated from the greater omentum laying in the pelvic cavity and was completely excised without tumor spillage. Histologically, the mass was a spindle cell lesion with severe atypism and some mitosis. Immunohistochemistry for anaplastic lymphoma kinase-1 revealed that the lesion was an IMF tumor. Because of its local invasiveness and its tendency to recur, this tumor can be confused with a soft tissue sarcoma. Increasing physician awareness of this entity should facilitate recognition of its clinical characteristics and laboratory findings.

Inflammatory myofibroblastic tumor of the lung in children: anaplastic lymphoma kinase (ALK) expression and clinico-pathological correlation

The inflammatory myofibroblastic tumor (IMT) is a rare neoplastic lesion with a high incidence in children and young people, and may arise in lungs, soft tissue, or viscera. It is recognized as a borderline tumor with the possibility to recur, undergo malignant transformation, and metastasize. IMT is composed of fascicles of bland myofibroblastic cells admixed with an inflammatory infiltrate consisting of lymphocytes, plasma cells, and eosinophils. We reviewed pulmonary IMT diagnosed at Garrahan Hospital in Buenos Aires, Argentina, during 12 years and examined the clinical, laboratory, and pathological features as well as molecular genetics. Eight pediatric cases were evaluated with a male-to-female ratio of 5:3 and a median age of 6 years at diagnosis. The most common lung localization was the upper lobe. All cases underwent surgical excision and no local recurrences were found. Five out of eight patients, including two cases with metastatic/multifocal lesions in the central nervous system (CNS), are alive and disease free after a median follow-up of 30 months. Anaplastic lymphoma kinase (ALK) expression was negative in all pulmonary samples by immunohistochemistry (IHC), however, rearrangement for ALK locus by fluorescence in situ hybridization was found in one lung and in two CNS samples. These findings may reflect higher sensitivity of the molecular biologic procedure compare to traditional IHC practice. In our pediatric experience, 25% of patients with lung IMT developed CNS lesions; therefore we consider that CNS screening in these patients should be considered, at diagnosis and later during follow up.