Verrucous Psoriasis: A Distinctive Clinicopathologic Variant of Psoriasis

Abstract

Psoriasis is capable of presenting in a variety of clinical and pathologic guises including a rarely described variant variably termed hypertrophic or verrucous psoriasis. Herein, we describe the clinical and pathologic attributes of a large series of patients with this unusual variant of psoriasis and distinguish it from other entities in the differential diagnosis. The histopathologic features and clinical and demographic attributes of a series of 12 cases from 12 patients were reviewed by a single dermatopathologist (MM). The 12 patients consisted of 7 males and 5 females with an average age of 61.8 years (males 38-93 years, females 41-71 years). Eight of the patients were Caucasian, 3 Hispanic and 1 African-American. Six of the lesions were located on the knees, 4 involved the elbows, and 2 were seen on the dorsum of the hands (metacarpal-phalangeal joint). The clinical appearance of the lesions consisted of flesh-toned to white mammillated plaques (8 cases) and coalesced papules (4 cases). Each of the biopsies showed regular psoriasiform epidermal hyperplasia with acanthosis, hyperkeratosis, and either spongiform neutrophilic or Munro micro-abscesses. In addition, each showed papillomatosis with bowing of the peripheral rete ridges toward the center of the lesion (buttressing). At high power, epidermal neutrophils were seen in particular surmounting the tips of the suprapapillary plates with accompanying serum. Hypergranulosis and koilocytic change were not observed in any of the lesions. Human papilloma virus (HPV) immunostaining and periodic acid Schiff (PAS) special staining for fungi were negative. Verrucous psoriasis is a distinctive variant of psoriasis with overlapping clinical and pathologic features that might prompt consideration of verruca vulgaris. The presence of epidermal papillomatosis and epidermal buttressing seen in these lesions is reminiscent of the histologic features of verruca vulgaris. Similarly, the presence of coalesced papules might prompt clinical consideration of verruca vulgaris as well. It is likely that this under recognized clinicopathologic entity represents a patterned response of the epithelium to repeated trauma/irritation typical of the anatomic locations that were encountered in this series. Recognition of this entity should preempt confusion with verruca vulgaris or other entities capable of producing wart-like epidermal changes.

Psoriasis under the microscope

“…The thickness of parakeratosis is highly variable, from two or three cell layers to thick compact and verrucous parakeratosis, associated with conspicuous papillomatosis. Verrucous variants of psoriasis may occur, especially on the knees, legs and dorsum of the hands 7 . Extremely thick parakeratotic cornified layer may lead to horn formation 8 …”

Erythrodermic verrucous psoriasis

“…VP is characterized clinically by symmetric hypertrophic verrucous plaques on an erythematous base and pathologically by overlapping features of both verrucae and psoriasis with negative HPV studies. Along with the psoriatic changes, these lesions typically display epidermal papillomatosis and epidermal buttressing but no koilocytic changes (1,4). VP has only been reported as individual plaques.…”

“…Verrucous psoriasis (VP) is a rare atypical presentation of psoriasis that can be a diagnostic and therapeutic challenge. This variant is characterized clinically by hypertrophic verrucous plaques on an erythematous base and pathologically by overlapping features of both verrucae and psoriasis (1)(2)(3)(4). We describe a patient with erythrodermic verrucous psoriasis in order to better characterize this rare variant and heighten the awareness of its unique presentation.…”

Psoriasiform Keratosis

“…30 We have seen several such cases in patients with known disseminated psoriasis who develop lesions that, histologically, have the classic features of either seborrheic keratosis or verruca vulgaris but additionally show overlapping features of psoriasis. These cases were not included in this study.…”