A 30-year-old female patient presented with progressive reticulate pigmentation of the neck, upper chest, back, cubital fossa, and axillae since the age of 15 years. The patient also complained of recurrent multiple tender nodules and plaques associated with sinuses and pus discharge over the axillae, groins, and buttocks which healed with scarring for 4 years. There were multiple pitted scars and hyperpigmented macules over the perioral area and cheeks. Scattered comedo-like lesions were present over the upper back, chest, cubital fossae, and buttocks. Histopathology from the pigmented lesion revealed thinning of the suprapapillary epidermis, epidermal hyperplasia with finger-like elongation of the rete ridges, and increased pigmentation of their lower part, suggestive of Dowling-Degos disease (DDD). Biopsy section from comedonal lesion showed dilated infundibulum and antler-like rete ridges suggestive of follicular DDD. We report a case of DDD with follicular involvement and hidradenitis suppurativa (HS) which is a rare association and can be explained on the basis of single underlying defect in follicular epithelial proliferation. DDD-HS has been shown to result from mutations in PSENEN, encoding a critical component of the γ-secretase complex.

Dowling-Degos disease (DDD) is a late-onset genodermatosis characterized by hyperpigmented macules on the flexures along with scattered comedo-like lesions and pitted acneiform scars. Follicular Dowling-Degos is a rare type of DDD, with only two reports so far. It presents with follicular papules and comedo-like lesions predominantly on the face and trunk. Dermoscopy of follicular DDD shows irregular star-shaped/Chinese letter pattern pigmentation along with comedo-like lesions. Herein, we describe diagnostic clues including dermoscopy in three patients of follicular DDD which can help in differentiating it from other disorders presenting with comedo-like lesions.

Dowling-Degos disease (DDD) and reticulate acropigmentation of Kitamura (RAK) are rare genodermatoses inherited as an autosomal dominant trait with variable penetrance. They are considered to be part of a spectrum of reticulate pigmentary dermatoses, characterized by the presence of hyperpigmented macules coalescing in a reticular fashion. The authors describe a 28-year-old male patient having hyperpigmented macules on the axillae, neck and face, reticulate acropigmentation of dorsum of the hands, forearms and feet, palmar pitting, and comedo-like lesions over back. The patient showed the unique clinical as well as histopathological overlap of both the rare diseases (DDD and RAK), substantiating the hypothesis that they represent two different features of a single entity with variable phenotypic expression.