Does malignant transformation of benign soft-tissue tumours occur? A clinicomorphological study of ten initially misdiagnosed soft-tissue sarcomas

Right atrial cardiac myxoma with malignant transformation to undifferentiated sarcoma: A case report

Generally, sarcomas arising from benign soft tissue are rare. Cardiac myxoma (CM) is a benign tumor, and few reports have described its malignant transformation. Herein, we documented a case of an 89-year-old man with prostate cancer and a 5-year history of a right atrium tumor without Carney complex. The tumor was resected surgically and had a myxomatous or gelatinous appearance. Microscopically, the tumor had two components: a sarcomatous area and myxomatous area. In the myxomatous area, typical myxoma cells were demonstrable and were strongly immunoreactive for immunohistochemistry (IHC) of calretinin. In the sarcomatous area, the epithelioid- to spindle-shaped cells with prominent atypia proliferated densely. The IHC profile of cells in the sarcomatous area was different from that of cells in the myxomatous area; MDM2-positive cells were found only in the sarcomatous area. Especially, the Ki-67 index and number of p53-positive cells in the sarcomatous area were higher than those in the myxomatous area. The transition of the two components was seamless. Thus, we made a diagnosis of CM with malignant transformation corresponding to undifferentiated pleomorphic sarcomas. This case suggests that CM may transform into sarcoma, albeit rarely.

Atypical lipomatous tumor/"well-differentiated liposarcoma" of the skin clinically presenting as a skin tag: clinicopathologic, immunohistochemical, and molecular analysis of 2 cases

Liposarcomas are extremely rare in the skin. When they involve the skin, it is usually by upward spread from a subcutaneous or deeper seated liposarcoma. Very rarely, liposarcoma metastasize to the skin or arise as a primary dermal lesion. We describe 2 cases of atypical lipomatous tumor "well-differentiated liposarcoma" located in dermis. Both presented clinically as a skin tag. The neoplasms arose in a 56-year-old female and a 69-year-old male patient. Both lesions were treated by excision and reexcision. In addition to classical morphology of atypical lipomatous tumor with evidence of lipoblasts and atypical adipocytes, immunohistochemistry with nuclear murine double-minute type 2 protein and cyclin-dependent kinase-4 expression as well as fluorescence in situ hybridization analysis showing an amplification of murine double-minute type 2 protein and cyclin-dependent kinase-4 were helpful to establish the diagnosis. None of the cases recurred after surgical treatment. These 2 cases show the importance of not to misdiagnose lesions which clinically may appear to be benign.

Biological continuum of benign, atypical, and malignant mesenchymal neoplasms - does it exist?

The characterization of specific cytogenetic and molecular abnormalities in benign and malignant soft tissue tumours has increased our understanding and knowledge of the biology of these rare neoplasms in recent years and has led to the modification of a number of traditional classification schemes. Contrary to popular belief, it is reasonable to propose that there exists a molecular, genetic, and morphological continuum of benign, atypical, and malignant mesenchymal neoplasms. The identification of characteristic molecular changes in benign lipomas, lipomas with minimal atypia, and atypical lipomatous tumours, well-differentiated liposarcomas supports the hypothesis of a stepwise process in the pathogenesis of these neoplasms. Not only are these findings important for our understanding of the biology of soft tissue tumours, but they also may increase diagnostic and prognostic accuracy.

Chondrosarcoma of the thumb arising from a solitary enchondroma

Secondary chondrosarcoma of the bone of the hand arising from a solitary enchondroma is a rare entity, with only 16 published cases in the literature. We report the clinicopathologic findings of a new case arising from a preexisting solitary enchondroma. A review of the literature is discussed.

Post-irradiation soft tissue sarcoma

From 1975 to 1993, 11 of 375 patients treated for soft tissue sarcoma presented with post-irradiation sarcoma. The mean time interval between irradiation therapy and onset of the second neoplasm was 15.8 years (4-31 years). The total radiation dosage ranged from 12 to 60 Gy with a mean of 40 Gy. All patients had complete staging including CT or MRI of the tumour site, and CT of the lung. Surgical resection was the treatment of choice. Wide margins could be achieved in 10 patients. One had a marginal resection. Tumours included malignant fibrous histiocytoma, haemangiosarcoma, rhabdomyosarcoma, malignant schwannoma, fibrosarcoma and undifferentiated sarcoma. All patients were reassessed in our outpatient clinic. After a mean follow-up of 4.7 years (1.0-11.5 years), only 1 patient had died because of the tumour. Although post-irradiation sarcomas are rather infrequently observed, these tumours must be suspected when alterations or symptoms occur in a previously irradiated region. Early detection provides the chance of curative, wide margin resection.