How is it Diagnosed?
Melasma is a common acquired hyperpigmentation disorder that appears as
symmetrical, brownish patches on sun-exposed areas, especially the face. Diagnosis is
primarily clinical, based on the appearance and distribution of pigmentation.
A thorough history is essential, focusing on onset, sun exposure, hormonal factors (e.g.,
pregnancy, oral contraceptives), and cosmetic use. The pigmentation typically affects
the cheeks, forehead, nose, and upper lip.
Wood’s lamp examination helps in determining the depth of pigmentation. Under
ultraviolet light, epidermal melasma shows enhanced contrast, while dermal melasma
appears less distinct, indicating deeper pigment deposition and poorer treatment
response.
Dermoscopy can further aid diagnosis by revealing characteristic pigment networks
and help differentiate melasma from other pigmentary disorders like lichen planus
pigmentosus, post-inflammatory hyperpigmentation, or freckles.
Biopsy is rarely required but may be performed in atypical cases or when malignancy is
suspected. Histology typically reveals increased melanin in basal and suprabasal layers
with no significant inflammation.
Laboratory tests are not routine but may be indicated to rule out underlying endocrine
causes like thyroid dysfunction or hormonal imbalances. Accurate diagnosis is vital for
appropriate management, including sun protection, topical depigmenting agents, and
sometimes laser or chemical peel therapies.