Differential Diagnosis for Hyperpigmentation
The following differential diagnosis is organized into categories to help guide the thought process:
- Single Most Likely Diagnosis
- Melasma: This is a common condition characterized by patches of hyperpigmentation, typically on the face, and is often associated with hormonal changes, sun exposure, and genetic predisposition.
- Other Likely Diagnoses
- Post-inflammatory hyperpigmentation (PIH): This condition occurs after inflammation or injury to the skin, leading to increased melanin production and resulting in hyperpigmented areas.
- Sun-induced hyperpigmentation: Prolonged exposure to sunlight can cause an increase in melanin production, leading to hyperpigmentation, especially in areas frequently exposed to the sun.
- Hormonal changes (e.g., pregnancy, menopause): Fluctuations in hormone levels can lead to changes in skin pigmentation, often resulting in hyperpigmentation.
- Do Not Miss Diagnoses
- Addison's disease: A rare endocrine disorder characterized by adrenal insufficiency, which can cause hyperpigmentation, among other symptoms. Missing this diagnosis could be life-threatening due to the potential for adrenal crisis.
- Hemochromatosis: A genetic disorder leading to iron overload, which can cause skin hyperpigmentation. Early diagnosis is crucial to prevent organ damage.
- Internal malignancy (e.g., melanoma): Although rare, some internal cancers can cause hyperpigmentation as a paraneoplastic syndrome. Early detection of cancer is critical for treatment and prognosis.
- Rare Diagnoses
- Erythromelanosis follicularis faciei et colli: A rare condition characterized by hyperpigmentation and erythema of the face and neck.
- Dowling-Degos disease: A rare genetic disorder leading to reticular hyperpigmentation of the skin.
- Acquired bilateral nevus of Ota-like macules (Hori's nevus): A rare condition causing hyperpigmentation, typically on the face, which can be mistaken for melasma but has distinct clinical and histological features.