Mesenchymal chondrosarcoma of the retroperitoneum. Report of a case diagnosed by fine needle aspiration biopsy with immunohistochemical, electron microscopic demonstration of S-100 protein in undifferentiated cells.

BACKGROUND: Mesenchymal chondrosarcoma (MC), first described in 1959 by Lichtenstein and Bernstein, is an uncommon tumor of the soft tissues and bone defined by the coexistence of nests of well-defined cartilaginous tissue within a proliferation of primitive mesenchymal cells. CASE: A 27-year-old, white female consulted a physician for a left lumbar mass associated with sciatica-type pain, asthenia, anorexia and weight loss. Abdominal computed tomography showed a 20-cm, retroperitoneal neoplasm that occupied the lower half of the left abdominal flank. Fine needle aspiration biopsy showed clusters of small round cells mixed with islets of mature cartilage. Immunomarking for electron microscopy, carried out with 15 nm of A protein/colloidal gold, showed specific immunoreactivity to S-100 protein in the nuclear chromatin, nucleoli, Golgi apparatus, plasma membrane and cytosol of cells with more developed organelles. CONCLUSION: The diagnosis of MC rests on recognition of the biphasic component of small, undifferentiated cells and cartilage islets. In aspirates with only undifferentiated cells, demonstration of ultrastructure-specific immunoreactivity to S-100 protein may contribute to the final diagnosis.

Mesenchymal chondrosarcoma. A cytogenetic, immunohistochemical and ultrastructural study.

A case of mesenchymal chondrosarcoma was studied. The tumor was near-tetraploid and the clonal structural chromosomal abnormalities included add(7)(p13), add(22)(q13), markers, and double minutes. The ultrastructural and immunohistochemical findings were consistent with the diagnosis. Strong immunoreactivity for desmin was an unusual, not previously reported, feature of the neoplasm.

Electron microscopy in the diagnosis of small round cell tumors of bone.

Small round cell tumors involving bone can present problems in differential diagnosis by light microscopy. In exploring the role of electron microscopy in this situation, seven small cell osteosarcomas and seven mesenchymal chondrosarcomas were examined by electron microscopy and compared with typical and atypical Ewing's sarcomas. There is much overlap in the ultrastructural features of these tumors, but electron microscopy is helpful to establish or confirm a diagnosis of typical Ewing's sarcoma and, if representative matrix is present, of small cell osteosarcoma.

A mesenchymal chondrosarcoma of a child with the reciprocal translocation (11;22)(q24;q12).

The reciprocal translocation (11;22)(q24;q12) was observed in a seven day culture from a mesenchymal chondrosarcoma of the bone, a tumor not characterized cytogenetically so far. We suggest that because of the presence of a similar cytogenetic abnormality, mesenchymal chondrosarcoma may belong to the wide group of "t(11;22)-small round cell tumors".