Common acquired nevus - Hair and Scalp
Nevi typically arise during childhood, adolescence, or very early adulthood and then senesce in later years. During pregnancy, existing nevi may darken and become noticeable to the patient. Compound nevi are more common in individuals with lighter skin phototypes; other forms of nevi (those on palms, soles, conjunctiva, and in the nail bed) are more common in individuals of African and Asian descent.
D22.9 – Melanocytic nevi, unspecified
400096001 – Melanocytic nevus
Differential Diagnosis & Pitfalls
- (skin tag)
- – typically macular, 2-5 mm, and with a blue hue
- Combined nevus – two types of nevi that are seen together in one lesion; most commonly blue nevus and dermal or compound nevus
- Recurrent melanocytic nevus – history of the initial biopsy is often critical for the dermatologist and/or pathologist. Recurrent nevi characteristically occur in women, 20-30 years of age, on the trunk within 6 months of the original biopsy. While many different clinical morphologies may be seen, it often manifests as a scar with variegated hyper- or hypopigmentation, linear streaking and halo, stippled and/or diffuse pigmentation patterns. While most cases do not pose a diagnostic challenge on histopathology, some specimens, especially partial biopsies, may look indistinguishable from melanoma on histopathologic grounds alone.
- Desmoplastic nevus – typically small (< 1 cm) skin-colored to erythematous to mildly pigmented papule or nodule on the extremity of a young adult (average 30 years of age). Histopathology reveals spindled to epithelioid melanocytes within a fibrotic stroma.