Lymph node metastasis of soft tissue tumors: a cytomorphologic study

To study the frequency of regional lymph node metastasis of soft tissue tumors (STT) and to evaluate the utility of fine needle aspiration cytology (FNAC) as an initial investigative modality.

A prospective and retrospective study of over 6 years (1998-2004) was performed to look for frequency of STT metastasizing to lymph nodes. FNAC of enlarged nodes was performed as a routine outpatient procedure after obtaining complete clinical details. Histopathology and immunohistochemistry were correlated where available.

Lymph node enlargement was seen in 23 of 241 patients with STTs, of which 19 cases showed involvement (7.88%), synchronous with primary in 12 cases and metachronous in 7 cases. The most common sites of primary tumor were the lower extremity and head and neck region with involved regional lymph nodes. STTs commonly involving lymph nodes were rhabdomyosarcoma and extraskeletal Ewing's/primitive neuroectodermal tumor (PNET); other rare tumors included malignant granular cell tumor, epithelioid hemangioendothelioma, mediastinal ganglioneuroblastoma, angiosarcoma and epithelioid sarcoma.

Lymph node aspirates should be examined for alien cells, particularly smears that are paucicellular and demonstrate cystic change. Lymph node metastasis of STT is rare and influences staging, treatment and prognosis. Enlarged regional nodes should be examined with FNAC.