Dowling-degos disease

A 30-year-old female presented with asymptomatic and brown colored skin lesions over the body for the past 8 years. On examination, there was symmetrical involvement of the neck, flexures [Figure 1a] and trunk in the form of multiple, and brown macules arranged in a reticulated pattern. Along with this, she also had perioral pits [Figure 1b] and few keratotic papules in groin [Figure 1c]. There was no history of similar lesions in the family. Histopathological examination showed filiform downgrowth with papillomatosis and increased pigmentation in the basal layer [Figure 2a], highlighted on Masson Fontana stain [Figure 2b]. Based on these typical clinical and histopathological findings, a diagnosis of Dowling-degos was made.

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Figure 1:

(a) Reticulate pigmentation of axilla, (b) Perioral pits, (c) Reticulate pigmentation of groin and Keratotic papules.

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Figure 2:

(a) HPE: (On H&E ×200) Epidermis shows filiform downgrowth with papillomatosis and increased pigmentation in the basal layer. Dermis shows minimal periadenexal lymphomononuclear infilterate. (b) Masson Fontana stained basal layer pigmentation (×100).

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Dowling-degos disease is a rare genodermatosis with an autosomal dominant inheritance. Common differential diagnosis includes other disorders of reticulate pigmentation such as Reticulate acropigmentation of Kitamura (acral pigmentation, lesional atrophy, and palmar pits), Galli-Galli disease (suprabasal dyskeratotic acantholysis), and Haber syndrome (erythema and telengiectasias on the face, and verrucous papules on the trunk).

There is no definitive treatment available for reticulate pigmentation disorders till date. Topical steroids, hydroquinone, retinoic acids, azelaic acid, and systemic retinoids have been used without definitive success. Among lasers-fractional CO₂ or Er: Yag laser has shown some efficacy in the previous case reports.