Pitfalls in the cytological diagnosis of tenosynovial giant cell tumor: An illustration of eight discordant cases.

Tenosynovial giant cell tumor (TSGCT) is a highly recurrent benign tumor of the extremities. Wide local excision is usually sufficient to achieve its recurrence-free outcome. However, that needs a confident pre-operative cytological diagnosis as TSGCT. Aspirates from this tumor express the characteristic polymorphic cytological pattern, enough to impose a definite diagnosis. However rarely so, inadequate sampling from smaller tumors or due to faulty techniques, and selective sampling from topographic clusters of any individual component may lead to wrong interpretation. An unorthodox location near the larger limb joints further complicates the diagnostic misery on occasions. Such tumors are amenable to incomplete removal and risk for future recurrence. In this report, we describe eight cases of TSGCTs that were cytologically diagnosed otherwise. The cytological features of these discrepant tumors and the factors attributable to such dilemma are elaborated. Finally, a possible remedy has been proposed at conclusion in order to avoid future inconveniences.