Anaplastic large cell lymphoma (ALCL) possesses a broad morphological spectrum. Currently, we present a case of ALK-positive ALCL presenting with an alveolar growth pattern in a 22-year-old Chinese female. This patient complained of a progressively enlarged mass in the right axillary region for 6 months. Excisional biopsy revealed a well-developed alveolar structure with nests of dyscohesive tumor cells separated by delicate fibrovascular septae. The large pleomorphic cells have irregular nuclei with prominent nucleoli and fine chromatin and abundant pale cytoplasm. The neoplasm stained positively for CD2, CD3ε, CD30, ALK1, EMA and cytotoxic molecules (TIA1 and Granzyme B). Cytogenetic study via interphase Fluorescence in-Situ Hybridization disclosed the rearrangement involving ALK gene. The patient received 6 cycles of CHOP chemotherapy and achieved complete remission. She is alive in good condition up to the present. Our case is biologically similar to the conventional ALK-positive ALCLs and may just represent an unusual morphological appearance.
Keywords: ALK; alveolar; differential diagnosis; immunohistochemistry.