Characterized by dark, velvety, thickened skin in flexural areas like the neck and axillae, often associated with insulin resistance.
McCune-Albright syndrome features large, unilateral café-au-lait macules with distinctive irregular, jagged "coast of Maine" borders.
Characterized by large, asymptomatic, sharply demarcated "cliff-drop" patches of dermal atrophy with a bluish-brown hyperpigmentation, typically on the back.
A large, unilateral, hyperpigmented patch with irregular borders, typically on the shoulder or upper trunk of adolescent males, which later develops coarse, dark hairs (hypertrichosis).
A specific phototoxic reaction to psoralens in perfumes (like bergamot oil), causing bizarre, streak-like or droplet-shaped patches of hyperpigmentation where the perfume was applied.
Also known as ashy dermatosis, this presents as asymptomatic, slowly expanding, ash-gray to blue-brown macules and patches with a sometimes-raised erythematous border.
A rare genetic disorder with generalized, patchy hyperpigmentation that is present at birth and increases in extent and darkness with age.
The third stage of this genetic disorder is characterized by a distinctive pattern of hyperpigmentation in swirling, whorled, or linear streaks that follow Blaschko's lines.
A form of primary cutaneous amyloidosis with intensely pruritic, hyperkeratotic papules that coalesce into thickened, brownish, rippled plaques, most commonly on the shins.
An uncommon variant of lichen planus presenting as dark brown to gray, ill-defined macules and patches in sun-exposed areas and flexures, without a significant inflammatory phase.
A form of primary cutaneous amyloidosis with pruritic, grayish-brown macules that have a characteristic "rippled" or confluent pattern, most often on the upper back.
Acquired hyperpigmentation on the face, presenting as symmetric, blotchy, tan or brown patches, typically on the cheeks, forehead, and upper lip, often triggered by hormones and sun.
A common, benign, congenital birthmark in infants, appearing as a flat, blue-gray, poorly defined patch on the lower back and buttocks.
A dermal melanocytosis similar to the Nevus of Ota, but affecting the shoulder and supraclavicular area, presenting as a mottled, blue-gray patch.
A dermal melanocytosis presenting as a mottled, blue-gray patch of unilateral hyperpigmentation on the face in the distribution of the trigeminal nerve, often involving the sclera of the eye.
Exogenous ochronosis from long-term hydroquinone use causes a paradoxical, sooty, blue-black or grayish-brown hyperpigmentation with papules.
A common fungal infection that can present as either hyper- or hypopigmented well-demarcated macules with a fine scale, typically on the upper trunk.
A very common acquired hyperpigmentation that occurs after any type of skin inflammation or injury, leaving a flat patch of discoloration in the same shape as the original lesion.
A benign condition of sharply demarcated, non-familial, hyperpigmented patches in a segmental or block-like pattern, usually on the trunk.
A rare reaction to eating raw or undercooked shiitake mushrooms, causing a distinctive, intensely pruritic, linear, whip-like (flagellate) erythematous eruption that heals with hyperpigmentation.
