birthmark

A birthmark is a permanent mark or stain on the skin that is present at birth or develops soon after. Birthmarks are common and usually harmless, though some can be a cosmetic concern or indicate an underlying condition. They are broadly categorized by appearance into pigmented birthmarks, which involve excess melanin or pigment, and vascular birthmarks, which involve blood vessels.

Pigmented birthmarks include various types such as congenital melanocytic nevi (moles present at birth), smaller moles, and café-au-lait macules. These marks range in color from light brown to dark brown or black and may vary in size. Vascular birthmarks arise from changes in blood vessels and include port-wine stains (capillary malformations), salmon patches (often called stork bites), and infantile hemangiomas, which may appear after birth and typically grow before gradually involuting over time.

Mongolian spots are a common type of pigmented birthmark found on the lower back or buttocks, especially in individuals with darker skin tones; they usually fade during childhood.

Causes of birthmarks vary. They may result from normal variations in skin development, genetic factors, or developmental anomalies in the skin or its blood vessels. Most birthmarks are not harmful, but a few may be associated with medical conditions or cosmetic concerns.

Diagnosis is usually clinical, based on appearance. Dermoscopy or imaging is rarely needed, and biopsy is reserved for suspicious or atypical lesions. Treatment is often unnecessary, but cosmetic concerns, functional issues (such as vision obstruction), or risk of complications may lead to interventions. Options include laser therapy, topical or surgical approaches, and, for certain vascular lesions, propranolol under medical supervision. Regular monitoring is advised if a birthmark changes in size, color, or shape or becomes symptomatic.