Skin Involvement by Hematological Neoplasms with Blastic Morphology: Lymphoblastic Lymphoma, Blastoid Variant of Mantle Cell Lymphoma and Differential Diagnoses

SIMPLE SUMMARY: Pathologists working with skin biopsies of different hematological malignancies via blastic morphology need to consider a broad spectrum of diseases that, despite similar blastic features, have different outcomes and require distinct therapeutic strategies. Therefore, a precise and prompt diagnosis is critical for patient management. The aim of our paper is to discuss, in detail, the clinical and pathological features of lymphoblastic lymphoma of B- or T-cell origin and mantle cell lymphoma, in particular its aggressive blastoid variant. Although mantle cell lymphoma rarely involves the skin, its blastoid variant is commonly encountered in cutaneous infiltrates, possibly due to the increased tendency of aggressive subtypes for skin involvement. When aggressive lymphomas are detected at cutaneous sites, a complete systemic work-up is critical. Besides blastoid mantle cell lymphoma and lymphoblastic lymphoma, other hematological malignancies with blastic characteristics and skin involvement are discussed. ABSTRACT: Hematological neoplasms sharing a blastic morphology may involve the skin. The skin may be either the primary site of occurrence of hematological malignancies with blastic features or cutaneous lesions are the first manifestation of an underlying systemic malignancy. The assessment of skin biopsies of hematological neoplasms with blastic features poses diagnostic problems and requires expert hematopathologists considering a wide range of differential diagnoses. The precise diagnosis of diseases sharing blastic features but with different outcomes and requiring distinct therapies is essential for patient management. The present paper mainly focuses on cutaneous involvement of the blastoid variant of mantle cell lymphoma and lymphoblastic lymphoma of B-cell or T-cell origin. The relevant literature has been reviewed and the clinical aspects, pathological features, prognosis, and therapy of both blastoid mantle cell lymphoma and lymphoblastic lymphoma involving the skin are discussed. A focus on other hematological entities with blastic features, which may involve the skin, to be taken into consideration in differential diagnosis is also given.