Ossifying fibromyxoid tumor misdiagnosed as follicular neoplasia. A case report

Ossifying fibromyxoid tumor: Fine-needle aspiration cytology findings of a rare soft tissue neoplasm

Ossifying fibromyxoid tumors (OFMTs) are rare tumors of uncertain origin and intermediate (rarely metastasizing) biologic potential, with characteristic morphology of an encapsulated tumor containing polygonal cells in an abundant fibromyxoid matrix surrounded by a peripheral layer of metaplastic lamellar bone. FNA cytology of OFMT has not been sufficiently reported and till date cytological features of only seven cases have been reported so far. We report another case of OFMT in a 55-year-old female presenting with longstanding swelling in thigh. On fine-needle aspiration, a tumor with moderate cellularity and myxoid areas was seen; coupled with compatible radiological findings, a diagnosis of OFMT was suggested. Establishing a correct diagnosis is important as although OFMT is benign in nature, local recurrences or rarely distant metastasis have been seen of this tumor. Hence, a high degree of suspicion with radiological correlation is of utmost importance for identification of this entity.

Ossifying fibromyxoid tumor of soft parts: a clinicopathologic study of 70 cases with emphasis on atypical and malignant variants

The ossifying fibromyxoid tumor of soft parts (OFMT) is an uncommon soft tissue neoplasm of uncertain lineage. Approximately 100 cases of OFMT have been reported. Although the majority behave in a benign fashion, very rare tumors with histologic and clinical evidence of malignancy have been reported. Criteria for malignancy in OFMT have not as yet been defined. Seventy cases of OFMT were retrieved from our consultation archives and studied with respect to patient age and sex, tumor site and size, growth pattern, percentage of typical OFMT, cellularity and nuclear grade, mitotic figures (MF)/50 high power fields (HPF), atypical mitoses, necrosis, vascular invasion, and the presence of bone. Immunohistochemistry for pancytokeratin, S-100 protein, smooth muscle actin, desmin, and collagen II was performed on a subset of cases. Follow-up information was obtained from the submitting pathologists and clinicians. The Fisher exact test was used for statistical analysis. Patients (39 male, 31 female) ranged in age from 14 to 83 years (median 49 years). The tumors occurred primarily as subcutaneous or deeply seated masses in the trunk and proximal extremities and ranged from 1 to 14 cm (median 4.0 cm). The percentage of typical OFMT present in each case ranged from 0% to 100% (median 70%), and bone was present in 44 cases (63%). Mitotic activity ranged from 0 to 40 MF/50 HPF (median 2 MF/50 HPF), necrosis was present in 12 cases (17%), and vascular invasion was seen in 8 cases (11%). High cellularity or high nuclear grade was seen in 14 and 13 cases, respectively. Immunohistochemical results were as follows: S-100 protein (33 of 55, 60%), pancytokeratin (5 of 48, 10%), smooth muscle actin (2 of 44, 5%), desmin (5 of 39, 13%), and collagen II (1 of 26, 4%). Follow-up (51 cases, mean 54 months, median 36 months, range 5-151 months) showed local recurrences in nine patients and metastases in eight patients. Currently, 41 patients are disease free, 6 are alive with disease, 4 are dead of disease, and 1 died of other causes. The presence of high cellularity (p = 0.002), high nuclear grade (p = 0.001), or >2 MF/50 HPF (p = 0.004) were significantly associated with the development of metastatic disease and local recurrence. Infiltrative growth was also associated with increased risk of local recurrence (p = 0.03). We conclude that the histologic spectrum of OFMT is broader than previously appreciated, as many clinically benign cases display moderate cellularity, nuclear enlargement, or have identifiable mitotic figures. Our results strongly suggest that OFMT with 1) high nuclear grade or 2) high cellularity and mitotic activity of >2 MF/50 HPF should be regarded as sarcomas with significant potential for metastasis and untoward outcome ("malignant OFMT"). The remainder can be considered within the spectrum of OFMT, recognizing that even these lesions possess a risk, albeit very low, of metastasis. Consequently, OFMT should be considered tumors of intermediate malignancy. Their line of differentiation remains unclear, although we suggest they may belong to the category of translocation-associated sarcomas, not all of which recapitulate a normal line of differentiation.

Cytologic diagnosis of ossifying fibromyxoid tumor of soft tissue: A case report

Ossifying fibromyxoid tumor (OFMT) of soft tissue is an uncommon, recently described neoplasm. It is usually, but not universally, a benign neoplasm and cases of metastatic so-called "malignant OFMT" have been reported. Although the histopathologic features of OFMT are well characterized, the same is not entirely true so far as the cytology literature is concerned. There are only three cytologic descriptions of OFMT to date to the best of our knowledge. A 62-year-old woman presented with a subcutaneous well-circumscribed nodular soft tissue mass at the upper end of the shoulder. X-ray and computed tomography revealed an incomplete shell of calcification surrounding the nodular mass along with foci of ossification within it. Fine-needle aspiration (FNA) cytology showed round to polygonal to spindle shaped neoplastic cells arranged in clusters, cords, and small aggregates and lying discretely in a mucoid background. Some osteoid-like material was also seen. The tumor was completely excised and histopathologic examination confirmed the diagnosis of OFMT. OFMT should be considered as a possibility in FNA cytology of myxoid soft tissue tumor especially with radiologic evidence of ossification.