Symmetric Facial Hyperpigmentation: Differential Diagnosis
The most common causes of symmetric dark (black-brown) hyperpigmentation on the face are melasma, post-inflammatory hyperpigmentation, and drug-induced pigmentation, with melasma being the most prevalent in darker skin types and predominantly affecting women due to UV exposure and hormonal influences. 1, 2
Primary Diagnostic Considerations
Melasma
- Melasma is the leading cause of symmetric facial hyperpigmentation, presenting as brown to black patches typically on the cheeks, forehead, upper lip, and chin 1, 2
- Predominantly affects women and darker skin types (Fitzpatrick III-VI), with UV exposure and hormonal factors (pregnancy, oral contraceptives) as primary triggers 1, 2
- Appears as tan to dark brown macules when epidermal, or blue-gray when dermal melanin is present 3, 4
Post-Inflammatory Hyperpigmentation (PIH)
- Results from excess melanin deposition following inflammatory skin conditions (acne, eczema, psoriasis, trauma) 2, 4
- History of preceding inflammatory lesion is the key diagnostic feature 5, 4
- Epidermal PIH appears tan to dark brown, while dermal PIH has blue-gray discoloration 3, 4
- More common and persistent in darker-skinned individuals due to labile melanocytes 4
Drug-Induced Hyperpigmentation
- Frequent cause of acquired symmetric hypermelanosis, with clinical presentation depending on the offending medication 2
- Identifying and discontinuing the causative agent is essential 2
- Common culprits include antimalarials, chemotherapy agents, NSAIDs, and psychotropic medications 2
Less Common but Important Causes
Addison's Disease (Adrenal Insufficiency)
- Presents with diffuse hyperpigmentation most pronounced on sun-exposed areas, including the face 6
- Pigmentation often precedes other systemic manifestations by months to years, making early recognition critical to prevent life-threatening adrenal crisis 6
- Associated with oral mucosal pigmentation, which helps distinguish it from other causes 6
- Most common cause in developing countries is tuberculosis 6
Peutz-Jeghers Syndrome
- Characterized by mucocutaneous pigmentation with dark brown or blue-brown macules (1-5 mm) on the vermilion border of lips (94%), buccal mucosa (66%), and perioral region 1
- Pigmentation typically appears in infancy and may fade in late adolescence 1
- Distinguished from simple freckles by presence on buccal mucosa and profuse periorificial distribution 1
- Requires evaluation for gastrointestinal hamartomatous polyps 1
Exogenous Pigmentation
- Hydroquinone-induced ochronosis can cause blue-black pigmentation, particularly with prolonged use of skin-lightening products 1
- Products containing mercuric iodide, phenolic derivatives, or hydroquinones (legally or illegally obtained) may cause symmetric facial darkening 1
Diagnostic Approach
Initial Assessment
- Wood's light examination helps differentiate epidermal (enhanced pigmentation) from dermal (unchanged or minimally enhanced) melanosis 7, 5
- Document skin phototype (Fitzpatrick classification) as darker skin types are more susceptible to pigmentary disorders 2, 8
- Obtain detailed history including:
Laboratory Evaluation When Indicated
- For suspected Addison's disease: morning cortisol, ACTH level, and ACTH stimulation test 6
- Thyroid function tests if autoimmune features present 7
- Consider vitamin B12 levels if nutritional deficiency suspected 6
Critical Pitfalls to Avoid
- Failing to examine the oral mucosa, which is critical for diagnosing Addison's disease and Peutz-Jeghers syndrome 1, 6
- Missing early Addison's disease when pigmentation precedes systemic symptoms, potentially leading to adrenal crisis 6
- Overlooking medication history, including topical skin-lightening products that may cause paradoxical darkening 1, 2
- Not recognizing that symmetric facial pigmentation can be the presenting sign of serious systemic disease requiring interdisciplinary evaluation 6
- Assuming all facial hyperpigmentation is cosmetic; melanoma and its precursors must be excluded 8