Pitfalls in the diagnosis of cutaneous lymphoma

Cutaneous lymphomas are primarily classified as cutaneous T-cell/natural killer (NK) cell lymphomas and B-cell lymphomas; their classification being of utmost importance for prognostic and therapeutic purposes. Despite certain distinguishing attributes related to both these categories of lymphomas, considerable overlaps and deviations from the usual features exist and can lead to misclassification. The objective of this review is to discuss the various pitfalls involving morphology, immunohistochemistry, and gene rearrangement studies, all of which pose challenges in classifying cutaneous lymphomas as either the T-cell/natural killer cell or B-cell type.