Intraocular inflammatory myofibroblastic tumor with ALK overexpression

We report a case of an intraocular inflammatory myofibroblastic tumor nearly filling the vitreous cavity of the eye of a 50-year-old man. The tumor was composed of a mixture of spindle cells and mixed inflammatory elements, including numerous plasma cells. The differential diagnosis included inflammatory pseudotumor and neoplastic mimics of this condition. Further investigation with immunohistochemistry revealed the mass to be composed of myofibroblasts, positive for smooth muscle actin stains and with weak anaplastic lymphoma kinase (ALK) expression in some tumor cells. Evaluation by fluorescence in situ hybridization revealed the tumor cells to have multiple copies of chromosome 2 and ALK but no rearrangement of the ALK gene. The authors propose that multiple copies of the ALK gene may be involved in inflammatory myofibroblastic tumor tumorigenesis, in addition to ALK gene rearrangements.     

ALK oncoproteins in atypical inflammatory myofibroblastic tumours: novel RRBP1‐ALK fusions in epithelioid inflammatory myofibroblastic sarcoma

ALK oncogenic activation mechanisms were characterized in four conventional spindle‐cell inflammatory myofibroblastic tumours (IMT) and five atypical IMT, each of which had ALK genomic perturbations. Constitutively activated ALK oncoproteins were purified by ALK immunoprecipitation and electrophoresis, and were characterized by mass spectrometry. The four conventional IMT had TPM3/4‐ALK fusions (two cases) or DCTN1‐ALK fusions (two cases), whereas two atypical spindle‐cell IMT had TFG‐ALK and TPM3‐ALK fusion in one case each, and three epithelioid inflammatory myofibroblastic sarcomas had RANBP2‐ALK fusions in two cases, and a novel RRBP1‐ALK fusion in one case. The epithelioid inflammatory myofibroblastic sarcoma with RRBP1‐ALK fusion had cytoplasmic ALK expression with perinuclear accentuation, different from the nuclear membranous ALK localization in epithelioid inflammatory myofibroblastic sarcomas with RANBP2‐ALK fusions. Evaluation of three additional uncharacterized epithelioid inflammatory myofibroblastic sarcomas with ALK cytoplasmic/perinuclear‐ accentuation expression demonstrated RRBP1‐ALK fusion in two cases. These studies show that atypical spindle‐cell IMT can utilize the same ALK fusion mechanisms described previously in conventional IMT, whereas in clinically aggressive epithelioid inflammatory myofibroblastic sarcoma we identify a novel recurrent ALK oncogenic mechanism, resulting from fusion with the RRBP1 gene. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

RANBP2 and CLTC are involved in ALK rearrangements in inflammatory myofibroblastic tumors

Inflammatory myofibroblastic tumors (IMTs) are rare soft tissue tumors occurring primarily in children and young adults. ALK gene rearrangements have been identified in this neoplasm, with fusion of the ALK gene at 2p23 to a number of different partner genes. Metaphase cytogenetic analyses of these tumors have been relatively few, however, and may help to identify additional variant partners. We report on an IMT from a 2-year-old boy with a karyotype of 45,XY,der(2)inv(2)(p23q12)del(2)(p11.1p11.2),-22. FISH showed ALK-RANBP2 fusion in this tumor. The breakpoint was cloned and the fusion was confirmed, making this the third reported case of IMT with ALK-RANBP2 fusion. In addition, we identified the ALK fusion partner in a previously reported IMT with t(2;17)(p23;q23) as CLTC, a gene reported to be involved in four other IMTs, and showed that the breakpoint involved a novel ALK-CLTC fusion. FISH evaluation of nine other IMTs identified CLTC as the fusion partner in one additional case, but RANBP2 was not involved in the remaining eight IMTs, suggesting that the variant partners involved in ALK rearrangements in IMTs are diverse.     

FNAC of inflammatory myofibroblastic tumour of the subcutis: a diagnostic dilemma

Inflammatory myofibroblastic tumour formerly also known as inflammatory pseudotumour, was recognized initially in the lung and has been described in other visceral organs. It's occurrence in the subcutis is not well documented and its cytological appearance may be misinterpreted as malignant. This is the first case report of inflammatory myofibroblastic tumour of the subcutis in pediatric age group. A 12 year old female child presented with a subcutaneous swelling in the left anterior chest wall. FNA was performed and the cytological appearances were interpreted as malignant. Histopathology and immunohistochemistry revealed an inflammatory myofibroblastic tumour of the subcutis. FNA cytology is not very helpful in distinguishing inflammatory myofibroblastic tumour from malignant lesions especially soft tissue sarcomas. Awareness of it's occurrence in the subcutis is of importance for it's proper identification and treatment.     

Fusion of ALK to the Ran-binding protein 2 (RANBP2) gene in inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal proliferation of transformed myofibroblasts, with a prominent inflammatory cell component, that can mimic other spindle cell processes such as nodular fasciitis, desmoid tumor, and gastrointestinal stromal tumor. Genetic analyses have recently demonstrated rearrangements of anaplastic lymphoma kinase (ALK), located at 2p23, in a subset of IMTs. Molecular characterizations have identified ALK fusions involving tropomyosin-3 and -4 (TPM-3 and -4), the clathrin heavy chain (CLTC), and the cysteinyl-tRNA synthetase (CARS) genes as fusion partners. Here we describe two IMTs with a novel ALK fusion that involves the Ran-binding protein 2 (RANBP2) gene at 2q13, which normally encodes a large (358-kDa) nucleopore protein localized at the cytoplasmic side of the nuclear pore complex. The N-terminal 867 residues of RANBP2 are fused to the cytoplasmic segment of ALK in the 1,430-amino acid RANBP2-ALK chimeric protein. Myofibroblasts that express RANBP2-ALK exhibit nuclear membrane-associated ALK staining that is unique compared to the subcellular localization observed with other ALK fusions in IMT, presumably attributable to heteroassociation of the fusion with normal RANBP2 at the nuclear pore. These findings expand the spectrum of ALK abnormalities observed in IMT and further confirm the clonal, neoplastic nature of these lesions.     

Fusion of the ALK gene to the clathrin heavy chain gene, CLTC, in inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is a rare, but distinctive mesenchymal neoplasm composed of fascicles of bland myofibroblasts admixed with a prominent inflammatory component. Genetic studies of IMTs have demonstrated chromosomal abnormalities of 2p23 and rearrangement of the anaplastic lymphoma kinase (ALK) gene locus. In a subset of IMTs, the ALK C-terminal kinase domain is fused with a tropomyosin N-terminal coiled-coil domain. In the current study, fusion of ALK with the clathrin heavy chain (CTLC) gene localized to 17q23 was detected in two cases of IMT. One of these cases exhibited a 2;17 translocation in addition to other karyotypic anomalies [46,XX,t(2;17)(p23;q23),add(16)(q24)].     

Epithelioid inflammatory myofibroblastic sarcoma treated with ALK inhibitor: a case report and review of literature

Epithelioid inflammatory myofibroblastic sarcoma is extremely rare and belongs to a variant of inflammatory myofibrobalstic tumor with aggressive clinical course. We describe a case of a 22 years old man presented with an abdominal huge tumor. Microscopically, the neoplasm cells were rounded and epithelioid in shape. Abundant interstitial edema and less myxoid stroma were also present together with an inflammatory infiltrate. Fluorescence in situ hybridization revealed that ALK gene presented mutation. After surgery the patient received chemotherapy with an anaplastic lymphoma kinase (ALK) inhibitor, crizotinib. The patient continues to be alive with disease for 16 months and has no recurrence. Although EIMS has a poor prognosis, this is the few successful case with sustained response of targeted therapy.     

ALK expression in pseudosarcomatous myofibroblastic proliferations of the genitourinary tract

AIMS: Pseudosarcomatous myofibroblastic proliferation of the genitourinary tract is rare and may develop after trauma or spontaneously. The aim of this study was to characterize further the clinicopathological features of these lesions and to examine their relationship to inflammatory myofibroblastic tumour (IMT). METHODS AND RESULTS: Twenty-seven cases of pseudosarcomatous myofibroblastic proliferation were analysed. There were seven males and 20 females; median age was 37 years (range 16-88). Most lesions were from the bladder (n = 21), while others were in the urethra, vulva, vagina, rectum and retrovesical space. Median tumour size was 30 mm (range 6-120 mm). Seven cases (25%) had a history of prior trauma or surgery. Three cases recurred locally but not destructively. The tumours had fasciitis-like features including bland spindle cells with evenly distributed chromatin, admixed inflammatory cells (mainly lymphocytes) and often a myxoid stroma. Immunohistochemistry showed positivity for smooth muscle actin in 14/20 cases, keratin in 8/19, desmin in 7/20 and anaplastic lymphoma kinase (ALK) in 10/21 cases. Fluorescent in situ hybridization was performed in six ALK+ cases; all were negative for ALK gene rearrangement. CONCLUSIONS: Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract may show ALK immunopositivity but do not show consistent ALK rearrangement. Given subtle morphological differences and more consistently benign behaviour, their relationship to inflammatory myofibroblastic tumour at other sites remains uncertain.