Inflammatory myofibroblastic tumor: comparison of clinicopathologic, histologic, and immunohistochemical features including ALK expression in atypical and aggressive cases

Anaplastic lymphoma kinase: role in cancer pathogenesis and small-molecule inhibitor development for therapy

Anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase in the insulin receptor superfamily, was initially identified in constitutively activated oncogenic fusion forms - the most common being nucleophosmin-ALK - in anaplastic large-cell lymphomas, and subsequent studies have identified ALK fusions in diffuse large B-cell lymphomas, systemic histiocytosis, inflammatory myofibroblastic tumors, esophageal squamous cell carcinomas and non-small-cell lung carcinomas. More recently, genomic DNA amplification and protein overexpression, as well as activating point mutations, of ALK have been described in neuroblastomas. In addition to those cancers for which a causative role for aberrant ALK activity is well validated, more circumstantial links implicate the full-length, normal ALK receptor in the genesis of other malignancies - including glioblastoma and breast cancer - via a mechanism of receptor activation involving autocrine and/or paracrine growth loops with the reported ALK ligands, pleiotrophin and midkine. This review summarizes normal ALK biology, the confirmed and putative roles of ALK in the development of human cancers and efforts to target ALK using small-molecule kinase inhibitors.

Anaplastic lymphoma kinase: signalling in development and disease

RTKs (receptor tyrosine kinases) play important roles in cellular proliferation and differentiation. In addition, RTKs reveal oncogenic potential when their kinase activities are constitutively enhanced by point mutation, amplification or rearrangement of the corresponding genes. The ALK (anaplastic lymphoma kinase) RTK was originally identified as a member of the insulin receptor subfamily of RTKs that acquires transforming capability when truncated and fused to NPM (nucleophosmin) in the t(2;5) chromosomal rearrangement associated with ALCL (anaplastic large cell lymphoma). To date, many chromosomal rearrangements leading to enhanced ALK activity have been described and are implicated in a number of cancer types. Recent reports of the EML4 (echinoderm microtubule-associated protein like 4)–ALK oncoprotein in NSCLC (non-small cell lung cancer), together with the identification of activating point mutations in neuroblastoma, have highlighted ALK as a significant player and target for drug development in cancer. In the present review we address the role of ALK in development and disease and discuss implications for the future.

Pulmonary artery sarcoma: a histologic and follow-up study with emphasis on a subset of low-grade myofibroblastic sarcomas with a good long-term follow-up

Primary sarcomas of the pulmonary artery are rare, with few series correlating histologic features with follow-up data. We present a series of 43 pulmonary artery sarcomas with primary intraluminal growth, 32 with follow-up information. Symptoms were generally related to shortness of breath and often attributed to recurrent pulmonary embolism. There was no sex predilection. There were 28 pleomorphic-fascicular sarcomas, ranging from relatively differentiated spindle cell myxofibrosarcoma to undifferentiated round-cell sarcoma, often with histologic heterogeneity and overlap. The remaining tumors were 7 osteosarcomas, 4 leiomyosarcomas, 1 rhabdomyosarcoma, and 3 intravascular low-grade myofibroblastic sarcomas. Of the pleomorphic-fascicular sarcomas, 2 demonstrated extensive fibrosis with hyalinization and pleomorphic tumor cells were confined to a luminal rim of neoplastic cells. Histologically, mitotic rate was significantly lower in low-grade myofibroblastic sarcoma than in the other histologic subtypes. Follow-up revealed that 2 of 3 intra-arterial low-grade myofibroblastic sarcomas were cured with no evidence of disease at long-term follow-up. The other tumor subtypes, which represented intermediate and high-grade sarcomas, demonstrated 5 survivors of greater than 3 years, none surviving without disease. The only parameters associated with prolonged survival, other than low-grade myofibroblastic phenotype, was age less than 40 years at onset of symptoms. We conclude that survival beyond 3 years is possible for primary pulmonary artery sarcoma, but cure without evidence of disease is currently possible only for the select subtype of intravascular low-grade myofibroblastic sarcoma.

Recurrence of inflammatory pseudotumor of the lung after eleven years of remission

The standard treatment of inflammatory pseudotumor of the lung is surgical excision. However, little data is available on steroid therapy in patients with the unresectable disease. Here, we report a patient with recurrent inflammatory pseudotumor of the lung with pleural involvement who had been successfully treated with corticosteroid eleven years previously. Like the previous treatment, retreatment with corticosteroid proved to be effective for the recurred lesion. In addition, the patient had developed extramammary Paget's disease and bladder cancer after the initial onset of inflammatory pseudotumor. Steroid therapy could be an optional modality in treating unresectable inflammatory pseudotumor, although long-term follow-up is definitely necessary.

Inflammatory pseudotumor of the thyroid gland showing prominent fibrohistiocytic proliferation. A case report

Inflammatory pseudotumor of the thyroid gland (IPT) appears to be exceedingly rare. Histologically, 14 previously reported cases demonstrated plasma cell granuloma variant. We report here an IPT showing a predominantly fibrohistiocytic proliferation that occurred in a 75-year-old Japanese woman. Histologically, the lesion was characterized by haphazardly arranged spindle cells, histiocytes having foamy cytoplasm containing intracytoplasmic brown pigments, and small lymphocytes. Immunohistochemical study demonstrated that the spindle cells were vimentin+, desmin-, muscle-specific actin+, cytokeratin-, endomysial antibody-, anaplastic lymphoma kinase-, CD34-- CD68+/-, CD99-, cyclin D1-, bcl-2-, and antifollicular dendritic cell antibody-. IPT showing a predominant fibrohistiocytic proliferation should be differentiated from various nonneoplastic or neoplastic disorders showing spindle cell proliferation and/or exuberant fibrosis. They include Riedel's thyroiditis, fibrous variant of chronic thyroiditis, papillary carcinoma with exuberant nodular fasciitis-like stroma, paucicellular variant of anaplastic thyroid carcinoma, and solitary fibrous tumor.

Marginal zone B-cell lymphoma arising from buccal mucosa resembling inflammatory myofibroblastic tumor of the soft tissue

We report here a case of marginal zone B-cell lymphoma (MZBL) arising from buccal mucosa resembling inflammatory myofibroblastic tumor (IMT) of the soft tissue. On a low-power field, the lesion is characterized by fibrous granulation tissue and numerous lymphoid follicles with or without atrophic small germinal center. A portion of the lymphoid follicles were surrounded by partial and/or complete thin pale cuff of centrocyte-like (CCL) cells on high power field. The thin rim of the lymphoid follicles contained CCL-cells, plasma cells, cells showing plasma cell differentiation and mature eosinophils. In contrast, the granulomatous areas contained were characterized by haphazardly arranged spindle cells, mature plasma cells, mature eosinophils, small-to-medium lymphocytes and histiocytes. Histologically, IMT was suspected. However, flow cytometry and immunohistochemical study demonstrated a monotypic nature of centrocyte-like cells, plasma cells and their precursor and confirmed the diagnosis of MZBL arising from the buccal mucosa. The differential diagnostic problems between IMT of the soft tissue and classical Hodgkin lymphoma and T-cell lymphoma have been discussed previously. However, the present case indicated that MZBL should be added to the differential diagnosis of IMT of the soft tissue.

Inflammatory myofibroblastic tumors of the genitourinary tract--single entity or continuum?

PURPOSE

Inflammatory myofibroblastic tumor of the genitourinary tract is a spindled soft tissue lesion that is often mistaken for sarcoma. These tumors have been described in numerous sites in the body and have been assigned many names. The relationship between inflammatory myofibroblastic tumor and other morphologically similar entities has been a long-standing source of controversy. We investigated whether inflammatory myofibroblastic tumors in adults and children are the same entity, and whether inflammatory myofibroblastic tumor is part of a biological spectrum that includes benign and malignant entities at opposite ends.

MATERIALS AND METHODS

We performed an extensive review of the literature.

RESULTS

The literature suggests that with evidence of anaplastic lymphoma kinase rearrangement and expression, the lesion is neoplastic rather than reactive, differentiating it from previously described lesions.

CONCLUSIONS

Inflammatory myofibroblastic tumor of the genitourinary tract should be considered a neoplasm of uncertain malignant potential, and routine surveillance and close clinical followup are recommended. Aggressive therapy (radical cystectomy, radiation or chemotherapy) is unwarranted given the indolent and often benign clinical course for the majority of cases. To understand the diagnostic and prognostic implications future emphasis should be placed on the link between genetic abnormalities, and clinical course, therapeutic response and ultimate outcome.

An inflammatory myofibroblastic tumor in liver with ALK and RANBP2 gene rearrangement: combination of distinct morphologic, immunohistochemical, and genetic features

Inflammatory myofibroblastic tumor is an intermediate-grade neoplasm with potential for recurrence and rare metastasis. Rearrangement of the anaplastic lymphoma kinase gene with variable fusion partners and anaplastic lymphoma kinase expression using immunohistochemistry are noted in about half of the tumors. We present a hepatic inflammatory myofibroblastic tumor from a 34-year-old man with an unusual rearrangement between the Ran binding protein 2 and anaplastic lymphoma kinase genes, as well as a peculiar round cell transformation of tumor cells and a unique nuclear membrane expression of anaplastic lymphoma kinase protein. As the fourth reported inflammatory myofibroblastic tumor with this fusion so far, we find that these genetic and morphologic features may be related to a poor clinical outcome. The diagnostic difficulty and other prognostic factors of inflammatory myofibroblastic tumor are also discussed.

Are tumefactive lesions classified as sclerosing mesenteritis a subset of IgG4-related sclerosing disorders?

BACKGROUND

The relationship between tumefactive lesions classified as sclerosing mesenteritis and IgG4-related sclerosing disorders (eg, lymphoplasmacytic sclerosing pancreatitis/autoimmune pancreatitis) remains uncertain.

AIMS

To review lesions coded as "sclerosing mesenteritis" for findings in keeping with IgG4-related sclerosing disorders.

METHODS

Inclusion in the study required available paraffin blocks for IgG4 staining and documentation of a mass lesion.

RESULTS

A total of nine mesenteric lesions (3-14 cm) were identified in 6 male and 3 female patients. On H&E-stained sections, all were characterised as loosely marginated fibroinflammatory processes with variable amounts of fat necrosis. Lymphocytic venulitis/phlebitis was identified in 8 of 9 cases. IgG and IgG4 expression in lesional plasma cells was assessed by immunohistochemistry. IgG4-positive plasma cells were counted in the areas of greatest density in >or=3 high power fields (HPFs). The highest number per HPF was recorded and a score assigned based on the following scale: <5/HPF, none/minimal; 5-10/HPF, mild; 11-30/HPF, moderate; >30/HPF, marked. The relative proportion of IgG4-reactive plasma cells to total IgG-positive plasma cells was assessed. IgG4-reactive plasma cells ranged from 0 to >100 in the most dense zones (3 cases, none/minimal; 4 cases, moderate; 2 cases, marked).

CONCLUSIONS

Although this study is limited by small numbers, findings suggest that some tumefactive lesions regarded as sclerosing mesenteritis may be a subset of IgG4-related sclerosing disorders.

Pediatric inflammatory myofibroblastic tumor of the trachea: a case report and review of the literature

Inflammatory myofibroblastic tumors (IMTs) are relatively rare entities of a distinct histologic appearance and benign clinical course. Although these lesions have been described in virtually every anatomic location, there are few documented reports with tracheal localization. We add to the short list of pediatric IMTs of the trachea, a 13-year-old boy that was referred to our pediatric respiratory unit for evaluation of his respiratory distress. In particular, we describe the clinical and pathologic features of this patient and present a review of all reported lesions in the available literature.

Benign Tumors and Tumorlike Conditions of the Lung

Context.—Benign tumors and tumorlike conditions of the lung are encountered in the pathologic evaluation of asymptomatic and symptomatic lung nodules. Since many of these lesions are uncommon, they can be diagnostically challenging.

Objective.—To review the current classification of benign lung tumors, with emphasis on histopathology and useful ancillary studies.

Data Sources.—The current World Health Organization classification system for lung neoplasms and review of relevant publications.

Conclusions.—Despite improved imaging techniques, benign lung nodules are encountered in wedge biopsy and resection specimens. Histopathology, immunohistochemistry, and molecular techniques ensure accurate pathologic diagnosis and have shed light on the histogenesis of these unusual lesions.

Inflammatory myofibroblastic tumor of spermatic cord in undescended testis

Inflammatory myofibroblastic tumor (IMT) is an uncommon condition and only a few cases of IMT in the spermatic cord have been reported, with none associated with an undescended testis. We present the case of a man with an undescended left testis who had an IMT involving the spermatic cord. He was treated with surgery and no adjuvant therapy afterward. He was disease free at 2.5 years of follow-up. A brief discussion of the pathologic features and management of the condition is also provided.

Asymptomatic inflammatory myofibroblastic tumor of the heart: immunohistochemical profile, differential diagnosis, and review of the literature

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) is an uncommon lesion, mainly occurring in children and young adults and extremely rare in the heart. IMTs are composed of differentiated myofibroblastic cells accompanied by inflammatory cells. Cardiac IMTs are considered biologically benign, but they may have fatal consequences depending upon the peculiarity of site. Because of their rarity in the heart, most knowledge is based on extracardiac lesions that have uncertain behaviour.

METHODS AND RESULTS

We investigated the morphologic features and the immunohistochemical profile of an intracardiac IMT, arising in the right outflow tract of an asymptomatic 11-month-old boy, by using a large panel of antibodies, many of them previously reported in extracardiac IMTs only. Results were compared with data of literature. After complete surgical excision of the tumor, the patient is disease-free at 1 year of follow-up.

CONCLUSIONS

The present case showed morphologic and immunohistochemical features characteristic of IMT. Immunohistochemistry was helpful for characterization and differential diagnosis. The immunoreactivity pattern (including calponin expression) was similar to that of extracardiac IMTs except for anaplastic lymphoma kinase 1 immunoreactivity, lacking in this benign intracardiac IMT but usually associated to favourable prognosis in extracardiac IMTs.

Inflammatory myofibroblastic tumor and low-grade myofibroblastic sarcoma: a comparative study of clinicopathologic features and further observations on the immunohistochemical profile of myofibroblasts

Inflammatory myofibroblastic tumor (IMT) and low-grade myofibroblastic sarcoma (LGMS) are intermediate- or low-grade malignant myofibroblastic neoplasms. In this study, the clinicopathologic profiles of 24 IMTs and 10 LGMS were compared with a focus on the immunohistochemical profiles of the neoplastic myofibroblasts. The primary antibodies used in this study were specific for the ultrastructural subcellular components: (1) *-smooth muscle actin (*-SMA), muscle-specific actin (MSA), calponin, and h-caldesmon for myofilaments; (2) fibronectin for fibronexus; (3) laminin for basal lamina; (4) desmin and cytokeratin for intermediate filaments. Anaplastic lymphoma kinase (ALK) alterations were examined by immunohistochemical means, with selective fluorescence in situ hybridization analysis. Histologically, IMT had inhomogeneous microscopic features with multi-component and multi-patterned architecture, whereas LGMS tended to be more uniform in appearance with a higher cellularity, more prominent nuclear hyperchromasia, and a more widely infiltrative growth pattern than IMT. Immunohistochemically, firstly, more than 90% of the cases of both IMT and LGMS expressed calponin, *-SMA, MSA, and fibronectin, almost all with a high expression level, and no cases were positive for h-caldesmon. Secondly, 33.3% (7/21) of IMTs and 40% (4/10) of LGMS were positive for desmin with a low expression level. The positive percentage for laminin was 81.8% (18/22) in IMT, but was 42.9% (3/7) in LGMS with a low expression level. Thirdly, 13.6% (3/22) of IMTs were positive for cytokeratin, but no expression was found in LGMS. ALK staining was found in 40.9% (9/22) of IMTs, and the presence of ALK gene rearrangements was confirmed by fluorescence in situ hybridization in 5 of 6 IMTs examined. However, neither ALK gene rearrangements nor ALK protein labeling was detected in LGMS (0/9). In summary, IMT and LGMS are both composed of cells displaying well-developed myofibroblastic differentiation, which frequently and extensively express actin-associated proteins (*-SMA, MSA, and calponin) and fibronectin, consistent with the ultrastructure markers (myofilaments and fibronectin fibrils). Laminin expression does not exclude a diagnosis of myofibroblastic neoplasms. ALK and cytokeratin, when positive, can be helpful in differentiating IMT from LGMS. LGMS is not a member of the family of ALK-positive tumors.

Exophytic inflammatory myofibroblastic tumor of the stomach in an adult woman: A rare cause of hemoperitoneum

Inflammatory myofibroblastic tumor (IMT) of the stomach in adults is extremely rare, with unpredictable prognosis. We present a 55-year-old woman with a gastric IMT. She experienced sudden abdominal pain 4 d previously. Physical examination showed mild abdominal tenderness in the hypogastrium, but no palpable abnormal abdominal mass. Abdominal CT showed a mass of approximately 8 cm in the gastrocolic ligament. On laparoscopic exploration, unexpected hemoperitoneum of approximately 1.5 L of blood was found, and an exophytic gastric mass of approximately 10 cm, appeared from the anterior wall of the gastric body along the greater curvature. Laparoscopy further showed that non-clotting blood in the abdominal cavity seemed to be from the gastric tumor. After conversion to open surgery for more precise evaluation of the cause of hemoperitoneum and the large friable tumor, gastric wedge resection, including the tumor, was conducted. The final diagnosis was consistent with IMT that originated from the gastric wall.

The anaplastic lymphoma kinase in the pathogenesis of cancer

Tyrosine kinases are involved in the pathogenesis of most cancers. However, few tyrosine kinases have been shown to have a well-defined pathogenetic role in lymphomas. The anaplastic lymphoma kinase (ALK) is the oncogene of most anaplastic large cell lymphomas (ALCL), driving transformation through many molecular mechanisms. In this Review, we will analyse how translocations or deregulated expression of ALK contribute to oncogenesis and how recent genetic or pharmacological tools, aimed at neutralizing its activity, can represent the basis for the design of powerful combination therapies.

Posttransplant Epstein-Barr virus-associated myogenic tumors: case report and review of the literature

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of different types of malignancies. While nonmelanoma skin cancers, lymphomas and Kaposi sarcomas are the most frequently reported malignancies after solid organ transplantation, EBV-associated smooth muscle tumors (EBV-SMT) after transplantation are rare and thus far only 18 cases in kidney recipients have been reported. A case of a 51-year-old kidney transplant recipient diagnosed with EBV-SMT is reported together with a review of the literature.

Inflammatory myofibroblastic tumours: where are we now?

Inflammatory pseudotumour is a generic term applied to a variety of neoplastic and non-neoplastic entities that share a common histological appearance, namely a cytologically bland spindle cell proliferation with a prominent, usually chronic inflammatory infiltrate. Over the last two decades, inflammatory myofibroblastic tumour (IMT) has emerged from within the broad category of inflammatory pseudotumour, with distinctive clinical, pathological and molecular features. IMT shows a predilection for the visceral soft tissues of children and adolescents and has a tendency for local recurrence, but only a small risk of distant metastasis. Characteristic histological patterns include the fasciitis-like, compact spindle cell and hypocellular fibrous patterns, which are often seen in combination within the same tumour. Chromosomal translocations leading to activation of the ALK tyrosine kinase can be detected in approximately 50% of IMTs, particularly those arising in young patients. This review will examine the clinical, pathological, and molecular genetic features of IMT and discuss an approach to diagnosis and differential diagnosis.

Percutaneous management of tumoral biliary obstruction in children

BACKGROUND

There is limited experience of percutaneous biliary interventions in children although they are safe and effective procedures.

OBJECTIVE

To evaluate the efficacy and safety of percutaneous management of tumoral biliary obstruction in children.

MATERIALS AND METHODS

Percutaneous biliary interventions were performed in eight children (six boys, two girls) with a mean age of 10.5 years (range 4-17 years). The interventions included percutaneous biliary drainage (five patients), percutaneous biliary drainage and placement of a self-expanding metallic stent (two patients), and percutaneous cholecystostomy (one patient). All patients had signs of obstructive jaundice and two had cholangitis.

RESULTS

All procedures were successful. No procedure-related mortality was observed. Bilirubin levels returned to normal in four of the eight patients. Findings of cholangitis resolved in the two affected patients after the procedure and antibiotic treatment. Two patients underwent surgery after percutaneous biliary drainage procedures. A self-expanding metallic stent was placed in two patients with malignancy and the stents remained patent until death.

CONCLUSION

Percutaneous biliary interventions can be performed safely for the management of tumoral biliary obstruction in children.

Idiopathic retroperitoneal fibrosis: clinicopathologic features and differential diagnosis

Idiopathic retroperitoneal fibrosis (IRF) is a rare disease often causing obstructive uropathy. We evaluated the clinicopathologic features of 24 patients with IRF to characterize the histopathology of the disease and to provide a framework for the differential diagnosis with other retroperitoneal fibrosing conditions. Retroperitoneal specimens were analyzed by light and electron microscopy and by immunohistochemistry. Most patients presented with abdominal/lumbar pain, constitutional symptoms, and high acute-phase reactants. Overall, 20 had ureteral involvement and 13 developed acute renal failure. The retroperitoneal tissue consisted of a fibrous component and a chronic inflammatory infiltrate with the former characterized by myofibroblasts within a type-I collagen matrix. The infiltrate displayed perivascular and diffuse patterns containing lymphocytes, macrophages, plasma cells, and eosinophils. The perivascular aggregates had a central core of CD20(+) cells and a mantle of CD3(+) cells in equal proportions. In the areas of diffuse infiltrate, CD3(+) cells outnumbered the CD20(+) cells. Most plasma cells were positive for the IgG4 isotype. Small vessel vasculitis was found in the specimens of 11 patients. Our study indicates that a sclerotic background with myofibroblasts associated with a diffuse and perivascular infiltrate mainly consisting of T and B lymphocytes may be a pathological hallmark of IRF.

Inflammatory myofibroblastic tumor of the liver

We report a case of hepatic inflammatory myofibroblastic tumor in a 26-year-old African American man who presented with right upper quadrant pain, weight loss, and fatigue during the previous year. Hepatomegaly was found on physical examination. Laboratory findings were significant for mild normocytic, normochromic anemia and elevated erythrocyte sedimentation rate. Imaging studies showed 2 contiguous masses suspicious for malignancy. A left partial hepatectomy was performed; the preoperative differential diagnosis was for angiosarcoma and hepatocellular carcinoma. The resected liver specimen showed 2 contiguous, firm, tan-white nodules that microscopically represented a proliferation of spindled myofibroblast cells set in an inflammatory and collagenized background. The spindle cells were strongly reactive for smooth muscle actin but negative for ALK-1. The morphologic and immunophenotypic findings, coupled with the clinical presentation, were consistent with an inflammatory myofibroblastic tumor of the liver.

Inflammatory myofibroblastic tumor with thrombocytosis and a unique chromosomal translocation With ALK rearrangement

We describe a case of inflammatory myofibroblastic tumor with an unusual constellation of clinical, pathologic, and genetic findings. A 7-year-old girl had an 11-cm abdominopelvic mass accompanied by thrombocytosis, anemia, elevated erythrocyte sedimentation rate, and elevated C-reactive protein. The inflammatory myofibroblastic tumor displayed unusual histologic features of zonal coagulative necrosis, high cellularity with a herringbone pattern, and tumor-associated osteoclast-like giant cells. The complex tumor karyotype included a translocation t(1;2)(q21; p23). Following resection, the laboratory abnormalities resolved. The patient is well and free of recurrence at 3 years following resection. This case raises interesting questions about clinical, pathologic, prognostic, and molecular genetic interrelationships in inflammatory myofibroblastic tumor.