Brain metastasis of ALK positive anaplastic large cell lymphoma after a long-term disease free survival in an old adult.

Anaplastic large cell lymphoma (ALCL) is a subtype of non-Hodgkin lymphoma composed of CD30-positive cells and now recognized as three different entities: primary cutaneous ALCL, primary systemic anaplastic lymphoma kinase (ALK)-positive (ALK+) ALCL and primary ALK-negative (ALK-) ALCL. ALK+ ALCL is supposed to have a better prognosis than ALK- ALCL. It is rarely metastasized to other sites, especially to the central nervous system (CNS). Herein, we present a rare case of systemic ALK+ ALCL which metastasized to the brain after a long-term disease free survival in an adult. Neuroimaging revealed a well-enhanced mass in the left frontal lobe. And it was completely resected. The results of the pathological and immunohistochemical studies were consistent with the metastasized ALK+ ALCL. The clinical findings, pathologic characteristics and treatment are described.