The role of histology in predicting recurrence of ‘type A’ thymomas

Spindle cell thymomas (type A) are benign tumors with an excellent prognosis. A few recent studies revealed aggressive behavior with local recurrences and extrathoracic metastases.

In this study, over 600 cases of thymic tumors were analyzed and identified 23 patients of pure spindle cell thymomas (WHO type A). Approximately 43% of these cases had recurrence or metastases during the follow-up period.

The presence of necrosis correlates with both relapse and extrathoracic metastases but not with the stage of diagnosis. None of the other clinical or histological features such as size, nuclear atypia, and mitotic activity, were correlated with the outcome parameters, such as stage at diagnosis, presence or absence of relapse, and extrathoracic metastases.

Histological atypia is fairly common in ‘type A’ thymomas. The presence of necrosis was associated with both loco-regional and systemic disease and none of the other clinical or histological features correlated with aggressive behavior.

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