Cytologic diagnosis of rhabdomyosarcoma in a child with a pleural effusion. A case report.
BACKGROUND
A pleural effusion in children is usually caused by infectious diseases; malignant effusion is very uncommon. In a case of a malignant effusion in a child, a pleura-based metastasis of a neoplasm with a typically high prevalence in childhood has to be considered. Examples are neuroblastoma, nephroblastoma, Wilms' tumor, hepatoblastoma, malignant germ cell tumor and rhabdomyosarcoma.


METHODS
A 4-year old boy presented with a unilateral pleural effusion. Cytologic examination of the effusion revealed malignant small round cells admixed with very large cells with atypical nuclei. In formalin-fixed cell blocks prepared for immunocytochemistry the cells expressed desmin and myf-4. The cytologic diagnosis was consistent with metastatic rhabdomyosarcoma. Subsequent computed tomography revealed a mass above the diaphragm, which was biopsied. Histologic examination of a needle biopsy specimen confirmed the diagnosis of rhabdomyosarcoma. Molecular examination revealed a PAX3-FKHR fusion transcript specific to the alveolar type of rhabdomyosarcoma.


CONCLUSIONS
This case illustrates the usefulness of immunocytochemistry on cell block preparations in diagnosing difficult cases of effusion cytology.
Theunissen
Paul
P
Department of Pathology, Atrium Medical Centre, P.O. Box 4446, 6401CX Heerlen, The Netherlands. p.theunissen@gozl.nl
Cremers
Martin
M
van der Meer
Syb
S
Bot
Freek
F
Bras
Johannes
J
D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D002675:Child, Preschool; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics / Q000556:secondary*; D008297:Male; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D016066:Pleural Effusion, Malignant / Q000473:pathology*; D011859:Radiography; D018232:Rhabdomyosarcoma, Alveolar / Q000000981:diagnostic imaging / Q000235:genetics / Q000556:secondary*; D014157:Transcription Factors
D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D015514:Oncogene Proteins, Fusion; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; C068686:Pax3 protein, mouse