BACKGROUND: Deep penetrating nevus is a variant of melanocytic nevi with histologic features that may be alarming and can be mistaken for malignant melanoma. We are presenting a review of the clinical findings and the histologic features of deep penetrating nevus in a series of 14 cases. OBSERVATIONS: Deep penetrating nevus occurs most commonly over the acral skin of young adults. Clinically, the lesions were diagnosed as pigmented nevus, blue nevus, or malignant melanoma. Histologically, deep penetrating nevus shows a wedge-shaped lesion extending to the deep dermis and the subcutaneous fat tissue. Nests and fascicles of pigmented melanocytes extended deep at the periphery of blood vessels, nerves, and the cutaneous adnexa. Low-grade cellular atypia is present and mitoses are rare. CONCLUSIONS: Deep penetrating nevus is a variant of benign pigmented nevi with deep dermal and subcutaneous involvement. The pattern should be recognized and differentiated from malignant melanoma.
BACKGROUND: Deep penetrating nevus is a variant of melanocytic nevi with histologic features that may be alarming and can be mistaken for malignant melanoma. We are presenting a review of the clinical findings and the histologic features of deep penetrating nevus in a series of 14 cases. OBSERVATIONS: Deep penetrating nevus occurs most commonly over the acral skin of young adults. Clinically, the lesions were diagnosed as pigmented nevus, blue nevus, or malignant melanoma. Histologically, deep penetrating nevus shows a wedge-shaped lesion extending to the deep dermis and the subcutaneous fat tissue. Nests and fascicles of pigmented melanocytes extended deep at the periphery of blood vessels, nerves, and the cutaneous adnexa. Low-grade cellular atypia is present and mitoses are rare. CONCLUSIONS: Deep penetrating nevus is a variant of benign pigmented nevi with deep dermal and subcutaneous involvement. The pattern should be recognized and differentiated from malignant melanoma.