Cytology of embryonal rhabdomyosarcoma: A cytologic, light microscopic, electron microscopic, and immunohistochemical study of seven cases

Abstract

A correlated cytologic and histologic study of seven cases of embryonal rhabdomyosarcoma is presented. The diagnosis of rhabdomyosarcoma was established by light and electron microscopy and immunohistochemistry of the operative specimens. The cytologic appearance of the smears corresponded well with the histopathologic findings. Cytologically, two main cell types were distinguished: a predominant primitive, small round cell with scant cytoplasm and a large cell with an abundant cytoplasm, sometimes tadpole- or ribbon-shaped. The tumor cells were often enclosed in a background of mucosubstances. The lack of cytologic features proving rhabdomyoblastic differentiation, such as cross-striation, necessitates the use of additional methods in the cytologic diagnosis of embryonal rhabdomyosarcoma. The value of the embedding technique for ultrastructural analysis and immunohistochemistry in the demonstration of desmin in aspirates is emphasized in the diagnosis of embryonal rhabdomyosarcoma.

Fine-Needle Aspiration Biopsy Diagnosis of Pediatric Neoplasms

“…The cell membrane may be partly surrounded by basal lamina. The nucleus is usually large with a prominent nucleolus [6,12,13]. Neuroblastoma: Neuroblastoma is a malignant tumor composed of primative neuroblasts derived from the sympathetic nervous system.…”

Cytoarchitectural Findings in the Diagnosis of Primary Soft Tissue Tumors

“…155 Aspirate smears from the usual form of embryonal rhabdomyosarcoma are composed of spindled and triangular cells interspersed with a smaller number of round cells embedded in a frequently myxoid stroma. 8,11,142 In the rarer botryoid rhabdomyosarcoma, cells are small and ovoid, with scant cytoplasm, and are arranged in small clusters in a myxoid background. The diagnosis should take into account the general cytologic picture and the clinical characteristics of the lesion: a young child displaying a grapelike, exophytic lesion in a body cavity (vagina, bladder, ear, etc.)…”

“…8,170 In the solidpattern round cell rhabdomyosarcoma, the aspirate is composed almost exclusively of small round cells with scant cytoplasm, arranged in clumps of varying sizes. 124 Immunocytochemistry and electron C D microscopy are of great value, particularly in poorly differentiated lesions, since they allow the demonstration of striated muscle markers, such as desmin and fast myosin, 29,124,142 but also of thick and thin filaments and rudimentary sarcomeres. 8,11,142 Cytogenetic analysis shows that most alveolar rhabdomyosarcomas display the chromosome translocation t(2;13)(q35;q14).…”

“…124 Immunocytochemistry and electron C D microscopy are of great value, particularly in poorly differentiated lesions, since they allow the demonstration of striated muscle markers, such as desmin and fast myosin, 29,124,142 but also of thick and thin filaments and rudimentary sarcomeres. 8,11,142 Cytogenetic analysis shows that most alveolar rhabdomyosarcomas display the chromosome translocation t(2;13)(q35;q14). 35,103 Atypical rhabdomyoblasts should not be confused with the regenerative rhabdomyoblasts observed in muscle injuries; their nucleus contains evenly distributed chromatin and a prominent nucleolus.…”

Rhabdomyosarcoma of the Urachus

“…1,3,4,7,8,10,12 It is usually classified into four histologic types: embryonal, botryoid, alveolar and pleomorphic. 2 Although rhabdomyosarcoma may arise anywhere in the body, the urachus is an extremely rare site.…”