Differential Diagnosis of Darkly Hyperpigmented Skin Lesions at Scapular Areas
Single Most Likely Diagnosis
- Tinea Versicolor: This is a common fungal infection caused by Malassezia species, characterized by irregular, scaly, hyperpigmented or hypopigmented patches, often localized to the upper body including the scapular area. The description of irregular patches, scaly with dyspigmentation matches closely with tinea versicolor.
Other Likely Diagnoses
- Seborrheic Dermatitis: This condition can present with scaly, hyperpigmented lesions, particularly in areas rich with sebaceous glands, including the upper back. While it's more commonly associated with the scalp, face, and ears, it can extend to other areas.
- Post-Inflammatory Hyperpigmentation (PIH): Following any inflammatory skin condition (like acne, eczema, or psoriasis) in the scapular area, PIH can occur, leading to darkly hyperpigmented patches. The history of a preceding inflammatory condition would support this diagnosis.
- Erythrasma: A bacterial infection caused by Corynebacterium, which can lead to well-demarcated, hyperpigmented, and slightly scaly patches, typically in intertriginous areas but can occasionally be found on the back.
Do Not Miss Diagnoses
- Malignant Melanoma: Although less likely given the description of multiple irregular patches, it's crucial to consider melanoma, especially if there's a history of changing lesions or if any lesion exhibits the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving).
- Lymphoma (Cutaneous T-Cell Lymphoma): Certain types of cutaneous lymphoma can present with hyperpigmented, scaly lesions. A diagnosis of lymphoma would significantly alter management and prognosis.
Rare Diagnoses
- Dowling-Degos Disease: A rare genetic disorder characterized by reticular pigmentation of the flexures, but it can occasionally present with more widespread hyperpigmentation, including the back.
- Erythema Dyschromicum Perstans: A rare condition of unknown etiology, characterized by the gradual onset of hyperpigmented macules that can coalesce into patches, often on the face, neck, and upper trunk, including the scapular area.