Trisomy 2 found in proliferative myositis cultured cell

Recurrent FOS rearrangement in proliferative fasciitis/proliferative myositis

Proliferative fasciitis (PF) and proliferative myositis (PM) are rare benign soft tissue lesions, usually affecting the extremities of middle-aged or older adults. Presenting as poorly circumscribed masses, they histologically show bland spindle cell proliferation in a myxoid to fibrous background and a hallmark component of large epithelioid "ganglion-like" cells in various numbers, which may lead to their misdiagnosis as sarcoma. PF/PM has been long considered as reactive, akin to nodular fasciitis; however, its pathogenesis has remained unknown. In this study, we analyzed the FOS status in 6 PF/PMs (5 PFs and 1 PM). Five PF/PMs occurred in adults, all showing diffuse strong expression of c-FOS primarily in the epithelioid cells, whereas spindle cell components were largely negative. Using fluorescence in situ hybridization (FISH), all 5 c-FOS-immunopositive tumors showed evidence of FOS gene rearrangement in the epithelioid cells. RNA sequencing in 1 case detected a FOS-VIM fusion transcript, which was subsequently validated by reverse transcriptase-polymerase chain reaction, Sanger sequencing, and VIM FISH. The one pediatric PF case lacked c-FOS expression and FOS rearrangement. c-FOS immunohistochemistry was negative in 45 cases of selected mesenchymal tumor types with epithelioid components that may histologically mimic PF/PM, including pleomorphic sarcoma with epithelioid features and epithelioid sarcoma. Recurrent FOS rearrangement and c-FOS overexpression in PF/PM suggested these lesions to be neoplastic. FOS abnormality was largely restricted to the epithelioid cell population, clarifying the histological composition of at least 2 different cell types. c-FOS immunohistochemistry may serve as a useful adjunct to accurately distinguish PF/PM from mimics.

Pseudosarcomas of soft tissue

One of the most common and important pitfalls in soft tissue pathology are the so-called pseudosarcomas. These lesions are nonneoplastic; however, their rapid growth, hypercellularity, cytologic atypia, and mitotic activity makes them prone to be misinterpreted as sarcoma. The most common of these lesions are fibroblastic/myofibroblastic and matrix-forming proliferations, including nodular fasciitis, proliferative fasciitis and myositis, ischemic fasciitis, massive localized edema, myositis ossificans, and bizarre parosteal osteochondromatous proliferation and related entities. Most of these lesions rarely recur following simple excision; therefore, their accurate recognition helps prevent excessive therapy.

Proliferative myositis: value of imaging

Imaging findings in a 52-year-old woman with proven proliferative myositis are described. US revealed preservation of continuous muscle bundles and patchy areas of hyperechogenicity, containing hypoechoic lines. MRI showed at T2-w sequences an ill-defined, hyperintense, intramuscular lesion, containing isointense lines. Subtotal enhancement, a nonenhancing geometrical web, and fascial enhancement were noted. In patients with painful growing masses, US and MRI correlation may suggest the diagnosis of proliferative myositis leading to biopsy, thus avoiding mutilating surgery.

Mosaic trisomy 2 in myelodysplastic syndromes and acute myeloblastic leukemias

We present a short report here of two more patients with trisomy 2 as the sole chromosomal abnormality in a hematologic malignancy. Although trisomy 2 is a recognized abnormality in neoplasms, particularly hepatoblastomas, to the best of our knowledge only three other cases have been reported with trisomy 2, in patients with a hematologic malignancy. The two cases presented here of myelodysplastic syndrome transforming to acute myeloblastic leukemia and chronic myelomonocytic leukemia showed trisomy 2 as the sole abnormality.

Clonal rearrangement of 15p11.2, 16p11.2, and 16p13.3 in a case of nodular fasciitis: additional evidence favoring nodular fasciitis as a benign neoplasm and not a reactive tumefaction

This article describes a case of nodular fasciitis with the karyotype 47,XY,+4/46,XY,add(15)(p11.2), t(16;16)(p13.3;p11.2). The presence of clonal chromosomal abnormalities in this case, as well as in three previously reported cases, indicates that nodular fasciitis is a benign neoplasm and not a reactive lesion.

Clonal chromosome abnormalities in a so-called Dupuytren's subungual exostosis

We report the first cytogenetic investigation of a Dupuytren's subungual exostosis. The clonal abnormalities found suggest that at least some of these heterotopic ossifications could be neoplastic in nature, instead of being a purely reactive process or exuberant growth in response to trauma.

Translocation 2;11 in a fibroma of tendon sheath

AIMS

To determine whether fibromas of tendon sheath represent a reactive fibrosing process or whether they are neoplastic, we investigated the chromosomes of the proliferating cells. A clonally occurring karyotypic abnormality would be an argument in favour of these fibromas being neoplastic.

METHODS AND RESULTS

A biopsy specimen of a fibroma of tendon sheath was cultured after collagenase exposure leading to dissociation of the tissue. The cultured cells were harvested after 4 days and chromosome analysis done according to standard procedures. Ten out of 20 karyotyped cells showed an identical chromosome abnormality characterized by a t(2;11)(q31-32;q12). The other 10 cells showed a normal 46,XX karyotype.

CONCLUSION

The clonally occurring chromosome abnormality found in this fibroma of tendon sheath suggests that this proliferation is neoplastic and not a reactive fibrosing process.

Chromosomal anomalies in a case of proliferative myositis

Proliferative myositis, a reactive lesion similar to proliferative fasciitis and nodular fasciitis, has only been cytogenetically described in one other report to date. This previously described case showed trisomy 2. Cytogenetic analysis and fluorescence in situ hybridization (FISH) of a proliferative myositis lesion in the present study did not reveal trisomy 2 but the following clonal translocation was observed: 46,XX,t(6;14)(q23;q32).