Follicular occlusion triad associated with reticulate pigmentary disorder: is there a genetic linkage?

Sir,

A 35-year-old, married man, carpenter by occupation, presented to our outpatient department with recurrent eruptions of acne-like lesions over face and painful deep boils (yielding foul smelling pus discharge) over the buttocks and thighs for the past 10 and 5 years, respectively. He had recurrent, painful pus discharging nodules over the scalp. He denied any history pertaining to systemic involvement. In addition, he had multiple light-colored, flat, non-progressive lesions all over the body since birth. There was a history of similar lesions in one of the patient's sister (among the 3 other siblings). Patient was a known case of chronic obstructive kidney disease for the past 10 years. There was a history of renal calculi involving left and right ureter, 10 and 15 years back, respectively, for which he was operated on both the occasions, following which he developed deranged renal function.

Patient had received treatment in the form of multiple courses of non-steroidal anti-inflammatory drugs and oral antibiotics with transient improvement. Examination revealed multiple polyporus pseudocomedones over face, neck, axilla, and upper trunk along with deep ice-pick and depressed scars, suggestive of healed lesions [Figure 1]. Multiple, tender nodules with sinuses discharging foul-smelling, purulent discharge was prominent on both the buttocks [Figure 2] and thighs. Multiple follicular papules were present over the scalp with scanty serous discharge [Figure 3]. Numerous hypopigmented macules ranging in size from 2 × 2 mm to 1 × 1 cm were present over trunk, bilateral upper, and lower limbs [Figure 4]. Rest of the mucocutaneous and systemic examination was unremarkable.

Figure 1

Polyporus comedones and ice-pick scars over face

Figure 2

Discharging sinuses over buttocks

Figure 3

Nodule over the vertex of scalp with sinus

Figure 4

Numerous hypopigmented macules ranging in size from 2 × 2 mm to 1 × 1 cm were present over back

Laboratory investigations revealed a low hemoglobin (8.6 g/dl) and deranged renal functions (Blood Urea −58 mg%, Serum creatinine −2.5 mg%). Urine for routine and microscopy did not reveal any abnormality. Biopsy from a representative hypopigmented macule from trunk showed a focal decrease in melanin in the basal layer of the epidermis. Accordingly, a diagnosis of follicular occlusion triad with dyschromatosis universalis hereditaria was made. Patient has been started on oral isotretinoin (0.5 mg/kg). Unfortunately, the patient lost follow up.

The association of hidradenitis suppurativa with severe or conglobate acne, and perifolliculitis capitis has been termed as follicular occlusion triad.[12] A new triad has been described by Loo, et al. in the form of hidradenitis suppurativa, Dowling-Degos, and multiple epidermal cysts.[3] Hidradenitis suppurativa is a misnomer, as it is not primarily a disorder of sweat gland. It is a chronic relapsing inflammatory skin disease characterized by recurrent draining sinuses and abscesses, predominantly in skin folds that carry terminal hair and apocrine glands. Currently, it is widely accepted to be an inflammatory disorder originating from hair follicle with secondary involvement of apocrine glands.[4] Autosomal dominant mode of inheritance has been proposed; however, the transmission rate is less than 50%, possibly due to polygenic inheritance, rigid disease definition, incomplete penetrance, and hormonal influence.[4] Recently, a study done in a large Chinese family with hidradenitis suppurativa identified a novel locus on chromosome 1p 21.1-1 q25.3, but this region was too wide to find the disease gene and further studies are required in families to identify the putative gene.[4] Dowling Degos disease, a reticulate pigmentary disorder of the flexures has been found to be associated with hidradenitis suppurativa on occasions.[35678] A primary follicular pathology in both the conditions has been postulated to be the reason for their coexistence; however, no genetic association has been defined between the two.[3] Nonetheless, to the best of our knowledge, dyschromatosis symmetrica hereditaria concurrent with follicular occlusion triad has not been described. Reticulate pigmentary disorders are a rather controversial topic in the recent literature, the genetic basis which is largely elusive; nevertheless, Dowling-Degos disease, dyschromatosis symmetrica hereditaria, dyschromatosis universalis hereditaria, and reticulate pigmentation of Kitamura have been proposed to be spectral. The genetic defects in DDD have been identified in these disorders namely KRT5 gene, gene locus mapping to chromosome 17 p13.3.[91011] Dyschromatosis symmetrica hereditaria has been linked to 6 q24.2-q25.2 gene in two Chinese families.[12] Autosomal recessive inheritance with linkage to 12 q21-q23 gene has also been described.[13] Dyschromatosis symmetrica hereditaria is caused by mutations in the ADAR1 gene on chromosome 1 q21.3 that encodes a double-stranded RNA-specific adenosine deaminase.[141516] Although Loo, et al.[3] have described the association of DDD and HS, we report here an association between DSH (a dyschromatosis related to DDD) and FOT (a triad that encompasses HS). Thus, the overlap of the possible causative genes between hidradenitis suppurativa and DSH might not just be a coincidence.