Virchows Archiv : an international journal of pathology
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Rhabdomyosarcoma (RMS) is currently classified into embryonal RMS, including its botryoid and spindle cell variants, alveolar RMS, including a solid variant, and pleomorphic RMS. In children and adolescents embryonal RMS occurs in a younger age group than alveolar RMS, and pleomorphic RMS is almost always seen in older adults. Most recently rare spindle cell and sclerosing, pseudovascular RMS have been reported in adults as well. ⋯ Follow-up information was available in five patients (range from 10 to 48 months) and revealed lung metastases in two patients who died of disease within a short period. In summary, spindle cell rhabdomyosarcoma represents a rare neoplasm in adulthood characterized clinically by a rather poor prognosis, and shows a broad morphological spectrum including most likely the sclerosing, pseudovascular variant. Immunohistochemically, tumour cells in RMS stain positively for CD 99 and WT1 as well, which is of importance in the differential diagnosis to other mesenchymal neoplasms, whereas fast myosin does not represent a reliable marker for RMS in adults.