METASTASIS OF UNKNOWN ORIGIN - THE ROLE OF FINE-NEEDLE ASPIRATION CYTOLOGY

Metastasis of unknown origin (MUO) manifests either as a tumor deposit in an organ, often cervical lymphadenopathy, or as a multiorgan carci nomatosis. As a diagnostic and therapeutic challenge, the definition o f its cell type and possibly its origin is imperative, although a limi ted diagnostic investigation is usually recommended. At Hines VA Hospi tal, from 1986 to 1994, there were 116 cases with admitting clinical d iagnosis of MUO, evaluated by fine-needle aspiration cytology (FNAC). The ages of patients ranges from 29 to 82 years (mean 56 years). All w ere male; Caucasians predominated. The FNAC examination with Diff-Quik and Papanicolaou smears were complemented with special and immunostai ns in 48 cases (41%) and electron microscopy in 93 cases (80%). The FN AC involved lymph nodes in 57 cases (49%), liver in 27 cases (23%), sk in in 22 cases (19%), bone in six cases (5%), lung in three cases (3%) , and pleura in one case (1%). The neoplasm was generally cell typed, and there were 60 adenocarcinomas/poorly differentiated carcinomas, 26 small-cell carcinomas (SCC), 23 squamous-cell carcinomas (SQCC), and six undifferentiated large-cell carcinomas. The primary source was def ined in 30 cases (26%), consisting of lung in 11 cases, prostate in ni ne, kidney in four, colon in four, pleura in one, and peritoneum in on e. Clinical correlation also supported a lung origin for the SCC, whil e the majority of the SQCC in upper and middle cervical lymph nodes we re considered head-and-neck tumors. Our results affirm that FNAC is a viable and simple procedure in MUO investigations. (C) 1998 Wiley-Liss , Inc.