Ossifying fibromyxoid tumour of soft parts: report of four cases including one mediastinal and one infantile

Abstract

Ekfors, T. O., Kulju, T., Aaltonen, M. & Kallajoki, M. Ossifying fibromyxoid tumour of soft parts: report of four cases including one mediastinal and one infantile. APMIS 106: 1124-1 130, 1998.Four cases of ossifying fibromyxoid tumour of soft parts are described. One of them was in the mediastinum, a hitherto unreported location of this rare neoplasm. Another was removed from the subcutaneous tissue of the head of a two-year-old girl, the youngest patient so far described. A peculiar feature of this tumour was haphazard spindle cell groups showing smooth muscle differentiation. One tumour was remarkably proliferative with 20 mitotic figures per 10 high power fields and 50% of cells positive for Ki-67 antigen. Immunohistochemical analysis revealed that all the tumows were diffusely positive for vimentin, and focally for S-100-protein. In addition to this the infantile tumour expressed focal a-smooth muscle actin, desmin and glial fibrillary acidic protein, while the mediastinal tumour expressed only a-smooth muscle actin and the highly proliferative one expressed none of these antigens. Background cells, including histiocytes, lymphocytes and mast cells were numerous. DNA cytometry analysis using both static and flow methods showed that the mediastinal tumour contained two cell clones, while the others were diploid. The proliferative fraction of cells (S plus G2 phases) was prominent in the proliferative and infantile tumours.

Ossifying Fibromyxoid Tumor: Modified Myoepithelial Cell Tumor? Report of Three Cases with Immunohistochemical and Electron Microscopic Studies

“…The most consistent findings were immunoreactivity of tumor cells for S-100 and the presence of EL by electron microscopy in the majority of cases studied, similar to the original observation of Enzinger et al [1]. These findings led the majority of subsequent authors to favor Schwann cell histogenesis of OFMT [6][7][8][9][10]. However, similarities between peripheral nerve sheath tumors and OFMT seem to be limited [2].…”

Ossifying Fibromyxoid Tumor of Soft Parts—A Clinicopathologic and Immunohistochemical Study of 104 Cases With Long-term Follow-up and a Critical Review of the Literature

“…2,3,8,11,18,26,49 However, it is our impression that some of the cases reported as OFTs in patients below the age of 10 years, are more plausibly explained by alternative diagnoses. Examples include a subcutaneous tumor in the head in a 2-year-old with distinct lesional smooth musclelike elements, 8 and a 25-cm S100 protein-positive retroperitoneal tumor with a corded pattern involving nerve roots, more consistent with an epithelioid peripheral nerve sheath tumor. 18 Another tumor composed of interlacing fascicles of spindle cells 3 also seems to be different from OFT.…”

“…9 To date, approximately 220 tumors have been published as OFTs. Most of these lesions have had classic morphology, 1,4,7,8,11,13,14,16,[21][22][23][24][25]28,30,32,34,[36][37][38][39][40][43][44][45][46][47]49 but more emphasis has recently been placed on the recognition of atypical and clinically malignant variants. 6,12,19,25,29,35,41,48,49 In 1 large series, it was suggested that either high nuclear grade or high cellularity in combination with a mitotic rate >2 mitoses per 50 HPFs predicts malignant behavior in OFT.…”

Ossifying Fibromyxoid Tumor: Invariable Ultrastructural Features and Diverse Immunophenotypic Expression

“…In addition to a few large series [1,[4][5][6][7], there are many case reports describing a single or a few cases [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Although the extremities, trunk, and head and neck are prevailing sites, unusual locations, such as the retroperitoneum and mediastinum, were also recognized [11,15,19]. OFMT shows characteristic microscopic features: ovoid tumor cells exhibit nodular growth pattern within a fibromyxoid stroma [1,4].…”

“…Ossifying Fibromyxoid Tumor were reported to be positive for desmin, smooth muscle actin, myosin, and muscle actin, indicating myogenic or leiomyogenic differentiation [11,25]. However, ultrastructural investigations have failed to demonstrate myofilaments and other organelles suggestive of myogenic differentiation [1, 5, 6, 10, 12, 14, 15, 17-20, 24, 26, 28].…”