Desmoplastic melanoma (DM) is a rare variant of melanoma that is histopathologically characterized by the dispersion of invasive tumor cells in a collagen-rich stroma. The tumor cells are usually amelanotic and predominantly fusiform in appearance. DM can be confused with…
Any melanoma, including the common variants superficial spreading, lentigo maligna, and acral lentiginous melanoma, may form an invasive tumor nodule. However, the presence of a prominent nodule does not equate a nodular melanoma (NM) subtype ( Fig. 15.1 ). According…
General Comments Melanocytic lesions of acral skin are at particular risk of being misdiagnosed for a variety of reasons. On the one hand, acral melanoma (AM) may have very subtle histologic features, particularly in the early in situ stage and…
Nomenclature Lentigo maligna melanoma (LMM) refers to a variant of melanoma that tends to occur on chronically sun-exposed skin of elderly Caucasians and is usually histopathologically characterized by a distribution of predominantly solitary units of melanocytes at the dermoepidermal junction.…
Microscopic examination and clinic-pathologic correlation represent the “gold standard” for the diagnosis of melanoma. Among experienced pathologists, the assessment of melanocytic lesions by histopathologic criteria is fairly accurate and reliable in most cases, but it cannot be expected to provide…
Combined melanocytic nevi are benign melanocytic proliferations with two (or more) histopathologic nevus phenotypes in the same clinical lesion. Their clinical importance lies in the diagnostic pitfall they pose—their possible confusion with melanoma. Knowledge of the clinical and histopathologic spectrum…
Features of traumatized or persistent nevi appearing at the site of prior surgery may mimic melanoma, a phenomenon recognized for several decades. The histologic distinction between a persistent nevus and a regressing melanoma may in some cases, especially in partial…
The so-called deep penetrating nevus (DPN) is a variant of a benign melanocytic nevus. It is composed of distinctive pigmented spindled, ovoid, or occasionally epithelioid melanocytes with a characteristically inverted triangle-like downward architecture. Its clinical significance lies in the potential…
Blue nevi (BN) and dermal melanocytoses share clinical, histologic, and molecular features. Clinically most lesions are characterized by bluish discoloration. Under the microscope there is an aggregate of melanocytes typically confined to the dermis unassociated with epithelium (i.e., there are…
The diagnosis of Spitz nevi and their distinction from melanoma is one of the most difficult tasks in neoplastic dermatopathology. Before a group of melanocytic proliferations was accepted as benign and named Spitz's nevus, similar lesions in children had been…