Follicular Porokeratosis at alae Nasi; A Case Report and Short Review of Literature.

Porokeratosis are disorders of keratinization, characterized histologically by a parakeratotic column, the cornoid lamellae, and clinically by a distinct peripheral ridge. Porokeratosis usually occurs on the trunk or extremities, and facial lesions are rare. Follicular involvement, identified by follicular localization of cornoid lamellae, is uncommon and described only in association with disseminated superficial actinic porokeratosis (DSAP) and porokeratosis Mibelli (PM). A 34-Year- old woman is presented with asymptomatic 1 cm plaque lesion with hyperkeratotic ridge and depressed center on her nose since three years. Histopathological examination of a biopsy revealed cornoid lamellae confined exclusively to the follicle.

What was known?

Facial follicular porokeratosis is a rare entity.

Introduction

Porokeratosis are disorders of keratinization characterized histologically by a parakeratotic column, the cornoid lamella, and clinically by a distinct peripheral ridge.[12] These are believed to be genodermatoses with an autosomal dominant mode of inheritance.[1] Porokeratosis is characterized by annular plaques with an atrophic center and hyperkeratotic edges clinically, although it has a wide variety of clinical manifestations. The various morphological types recognized are: Porokeratosis of Mibelli (PM) disseminated superficial actinic porokeratosis (DSAP), porokeratosis palmaris et plantaris disseminata (PPPD) and linear porokeratosis (LP).[3] The lesions are inherited as an autosomal dominant condition, but frequently sporadic cases are seen. Exact pathogenesis is not known but an abnormal early keratinocyte apoptosis accompanied by dysregulation of terminal differentiation (keratinization) has been suggested for pathogenesis of cornoid lamella.[4]

Case Report

A 34-year old woman presented with asymptomatic lesion on her nose. On physical examination, there was a one cm plaque, which had hyperkeratotic ridge and depressed center on the right site of the nose [Figure 1]. The lesion appeared three years before and didn’t expand. Family history was non-contributory. She was otherwise healthy with no known history of other disease or drug allergy. No involvement of the trunk, extremities or mucous membranes was observed, and the patient was otherwise healthy with no developmental problems. The patient denied worsening of the lesions with sun exposure. Histopathological examination of a biopsy taken from the edge of the nasal lesion revealed cornoid lamellae confined exclusively to the follicle and a few area overlying an absent granular layer [Figure 2].

Figure 1

1 cm plaque, which had hyperkeratotic ridge and depressed center on the right site of the nose

Figure 2

Cornoid lamellae confined exclusively to the follicle and a few area overlying an absent granular layer

Discuscion

Porokeratosis usually occurs on the trunk or extremities, and facial lesions are rare. Two patient were reported with facial porokeratosis by Nabai et al. first in 1979.[5] There have been a few reports of exclusive facial involvement in porokeratosis, with skin lesions mostly over or near the nose.[1678910] Follicular involvement, identified by follicular localization of cornoid lamellae, is uncommon and described only in association with other subtypes such as DSAP, PM, and exclusive follicular cornoid lamella in follicular porokeratosis.[411]

In 1893, Mibelli named porokeratosis based on the assumption that the columns of parakeratosis emerge from the ostia of eccrine ducts. In the same year, Raspighi emphasized the plugging of the follicular infundibulum and acrosyringium of porokeratosis.[1213] Follicular involvement in the context of DSAP and PM has been discussed recently. There were nine well documented reports follicular porokeratosis in the English literature [Table 1]. Four of them were located on face and five of them located at extremities and the body. On histopathological examination, follicular cornoid lamellae were noticed first by de Almeida et al. In 2007.[14] Minami-Hori et al. reviewed the locations of cornoid lamellae in 86 porokeratosis lesions from 73 patients. Of these, 33 lesions from 32 patients were related to follicular infundibulums including consecutive sections, and there was no correlation between clinical subtype and the association of cornoid lamellae with cutaneous appendages. Presentation exclusively on the face seems to have no correlation with follicular involvement of the cornoid lamellae.[16] Pongpudpunth et al. published a case that had clinically characteristic DSAP located on the extremities and body, which were characterized histopathologically by follicular involvement.[11] In English literature, 2 nasal follicular porokeratosis patients have been described in addition to our patient. Our patient presented with only one lesion on her right alae nasi. On histopathologic examination solar elastosis was not shown, whereas, Wang at al showed solar elastosis histophatologically, different from our case.[9] While follicular porokeratosis is accepted as a distinct histopathologic entity in some publications, but it didn’t enter clinical classification.

Table 1

Follicular porokeratosis cases reported previously in the literature, and our case

İn conclusion, porokeratosis should be considered when atrophic skin lesion is seen on nose, although a rare condition. Histopathology in the diagnosis of all dermatological lesions is extremely important as in porokeratosis. Histophatologically, follicular porokeratosis is different from classic porokeratosis in terms of placement of parakeratotic columns in follicular infundibulum. Pathologists having knowledge of this new histopathologic entity will help dermatologists in identifying new cases of follicular porokeratosis.[17]

What is new?

Facial follicular porokeratosis may present without solar elastosis.