Rhabdomyosarcoma with epithelioid morphology: A challenging cytologic diagnosis in a pleural effusion
Recommended Citation
Rodgers S, Datta L, Perry KD, and Stone CH. Rhabdomyosarcoma with epithelioid morphology: A challenging cytologic diagnosis in a pleural effusion. Diagn Cytopathol 2021.
Document Type
Article
Publication Date
5-18-2021
Publication Title
Diagnostic cytopathology
Abstract
Rhabdomyosarcomas (RMS) are rare malignant skeletal muscle tumors that present more commonly in pediatric populations. The WHO currently classifies RMS into four types, embryonal, alveolar, pleomorphic, and spindle cell/sclerosing variants. Epithelioid rhabdomyosarcoma (EpiRMS) is another rare, recently described subtype of RMS presenting in older patients with a male predominance and has a rapidly progressive clinical course with frequent metastases. EpiRMS closely mimics poorly differentiated carcinoma or melanoma, demonstrating discohesive large epithelioid cells with abundant eosinophilic cytoplasm, frequent glassy cytoplasmic inclusions, large vesicular nuclei, and prominent nucleoli. We present a case of metastatic rhabdomyosarcoma with features reminiscent of EpiRMS presenting as a pleural effusion, closely followed by an inguinal lymph node biopsy. The malignant cells in the pleural fluid were diffusely positive for desmin, negative for MyoD1, myogenin, S100 and SOX10, and retained INI-1 expression. Subsequent lymph node biopsy demonstrated identical malignant epithelioid cells that were positive for desmin, myoD1 and myogenin, and a cytological diagnosis of "metastatic rhabdomyosarcoma, favor epithelioid rhabdomyosarcoma" was given considering the concurrent lymph node biopsy morphology and immunoprofile. A diagnosis of rhabdomyosarcoma, though rare and challenging, should not be overlooked when considering malignant cells with an epithelioid morphology in cytology specimens.
PubMed ID
34004052
ePublication
ePub ahead of print
