To the Editor:
We read with great interest the extraordinary case report entitled “Facial Follicular Porokeratosis: A Case Report” by Wang et al,1 which was published in a recent issue of the American Journal of Dermatopathology. In that article, the author described a 25-year-old white woman with an asymptomatic, erythematous, thin plaque with an edge of scale on the nasal supratip for 1 year. A complete skin examination failed to reveal additional lesions elsewhere. The biopsy showed cornoid lamellae centered exclusively in follicular infundibula, and at the base of the cornoid lamellae, there was loss of the granular layer and numerous dyskeratotic cells. It represents the first report of follicular porokeratosis solely involving the face.
Recently, we had the opportunity to observe very similar findings. A Brazilian 19-year-old man noted asymptomatic cutaneous lesions, which remained static (without centrifugal growth), approximately 4 years prior. The family history was noncontributory. He was otherwise healthy with no known history of other diseases.
The patient denied worsening of the lesions with sun exposure. On physical examination, there were 0.2- to 1.0-cm multiple erythematous keratotic papules with a raised double-edged border, in the distal part of the nose (Figs. 1A, B). There were no other skin lesions.
The patient had undergone 2 punch biopsies that were inconclusive. Subsequently, we performed a third incisional skin biopsy with multiple serial sections (with representation from the edge of the lesion) of which histopathological examination revealed cornoid lamellae confined exclusively to the follicle. The granular layer immediately beneath the parakeratosis was absent (Figs. 2A, B). Therefore, the histopathological features were also consistent with follicular porokeratosis. Follicular porokeratosis is a rare variant of porokeratosis, with only 5 reports in the literature. We report, to the best of our knowledge, the second case of follicular porokeratosis on the face.
Porokeratosis, a relatively rare cutaneous disorder of abnormal keratinization, is clinically characterized by distinct peripheral keratotic ridge that histologically corresponds to cornoid lamellae.2 It was first described by Mibelli in 18893 and since then, many other clinical variants have been described besides porokeratosis of Mibelli, such as disseminated superficial actinic porokeratosis; linear porokeratosis; plantaris, palmaris, et disseminata, and punctate porokeratosis.4,5 The condition may be familial, inherited in an autosomal dominant fashion with peak onset in childhood, or sporadic and of later onset. Men are more commonly affected than women.6
The clinical presentation defines and differentiates these subtypes. In porokeratosis of Mibelli, for example, annular plaques (usually >1 cm) with a raised border, central furrow filled with keratotic material, and a tendency to enlarge centrifugally are seen in non-sun-exposed areas.7 They have a predilection for the limbs, although the face, genitalia, oral mucosa, and cornea may also be affected.6,8,9 In disseminated superficial actinic porokeratosis, multiple small lesions, with usually less than 1 cm and a slightly raised hyperkeratotic ridge without a distinct furrow peripherally, are seen in a sun-exposed distribution, particularly the limbs.7
Facial involvement in porokeratosis is rare.1,10 It has been described in porokeratosis of Mibelli8,11 and disseminated superficial actinic porokeratosis.12-15 Porokeratosis of Mibelli presents distinct clinical characteristics from our patient: lesions are usually larger than 1 cm, located most often in non-sun-exposed area, and also tend to enlarge centrifugally. In disseminated superficial actinic porokeratosis, the facial involvement is uncommon. In addition, it rarely occurs exclusively in the face is even rarer,13,14 with only a few reports in the literature. As Wang et al, we also considered disseminated superficial actinic porokeratosis as a possible diagnosis for our patient. However, he had keratotic papules with a raised double-edged border. In addition, the lesions were verrucous. In disseminated superficial actinic porokeratosis, the lesions have slightly raised hyperkeratotic ridge.7 Furthermore, the biopsy lacked the solar elastosis and epidermal atrophy, typically seen in disseminated superficial actinic porokeratosis.
It is known from the literature that the follicular porokeratosis is a rare histopathological variant of porokeratosis, which is characterized by the presence of cornoid lamellae located exclusively in the follicular infundibulum. Up to now, there have been only 5 cases reported in the literature. One case is disseminated superficial actinic porokeratosis on arms and legs.16 Two cases are porokeratosis of Mibelli, on the extremities and buttocks.6,16 Recently, Pongpudpunth et al7 reported a case in a 40-year-old man with scaly red papules in a follicular distribution on the upper extremity. They believe that their case is unique because of the clinical and histological presentation and then proposed the term “follicular porokeratosis” as a clinical and histological distinct entity and not merely a histologic variant of the porokeratosis of Mibelli described in the literature so far. The clinical presentation of the new entity described by Pongpudpunth et al7 is that of multiple, small (<1 cm), persistent or static, follicle-centered lesions in either a photograph or a nonphotograph distribution. Finally, Wang et al published the most recent case of follicular porokeratosis, which represented the first report of follicular porokeratosis affecting only the face.
Coincidentally, our case is almost identical to the one published in the American Journal of Dermatopathology because there was involvement of only the distal part of the nose by lesions smaller than 1 cm. The histopathological findings were also similar (with cornoid lamellae limited to the follicular infundibulum and absence of solar elastosis and epidermal atrophy).
In summary, to our knowledge, this is the second report of follicular porokeratosis affecting only the face. We agree with Wang et al that follicular porokeratosis is a unique histopathological variant of porokeratosis and may have a distinctive clinical presentation.
Virna Lygia L. Rocha-Sousa, MD*
Juliana Bastos Costa, MD*
Thomas de Aquino Paulo-Filho, MD*
Keyla Borges Ferreira Rocha, MD†
Pedro Bezerra da Trindade-Neto, MD, PhD*
Departments of *Dermatology; and †Pathology, Federal University of Rio Grande do Norte, Natal, Brazil
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