Ultrasound-guided fine needle aspiration cytology of a primary lymph node leiomyoma: a flexible procedure for a complex case

Abstract

Background: A primary lymph node leiomyoma diagnosed by fine needle aspiration cytology (FNAC) is reported.

Case: A 22-year-old male complained of right groin swelling; ultrasound examination (US) showed a lymph node containing a 20-mm hypoechoic nodule. The residual lymph node was oval, with a well-characterized cortex and hilum. US-FNAC of the nodule showed oval spindle cells embedded in fibrillar matrix. Nuclei were naked and oval with dispersed chromatin but without nucleoli. Immunocytochemistry showed positivity for vimentin and actin, and negativity for cytokeratin, S100, CD23 and CD31. A smear of the residual lymph node showed a reactive lymphoid cell population. FNAC diagnosis was mesenchymal cell proliferation with smooth muscle phenotype; a lymph node is part of the lesion. A CT scan did not detect any inguinal or abdominal mass. The surgical sample was a lymph node containing a spindle cell tumor, which was actin and desmin positive, and S100, CD21, HMB45, CD23 and CD31 negative; MIB1 was positive in <5% of the cells. The residual lymph node was normal.

Conclusion: The final diagnosis was primary benign leiomyoma in a lymph node. US-FNAC may frame complex lymph node lesions and provide treatment options.