11cu.wallner

Verrucous Porokeratosis of Mibelli on the Buttocks Mimicking PsoriasisJuliann S. Wallner, MD; James E. Fitzpatrick, MD; Sylvia L. Brice, MD T h e t y p i c a l p re s e n t a t i o n o f p o ro k e r a t o s i s o f small keratotic papules and enlarge centrifugally to Mibelli is of a solitar y plaque with a prominent form annular or serpiginous lesions, ranging from a raised border cleaved by a central furrow. The few millimeters to several centimeters in diameter.
central por tion of the plaque is usually slightly Lesions are usually asymptomatic but can be pru- atrophic. The plaques var y in size from a few mil- ritic. Although onset can occur at any age, poro- limeters to several centimeters in diameter and keratosis usually appears during childhood. Sporadic tend to be acrally distributed, though they can cases, however, generally occur later in life. Men occur on any par t of the body. We repor t an u n u s u a l c a s e o f v e r r u c o u s p o ro k e r a t o s i s o f Lucker et al1 and Stone et al2 both described Mibelli, localized to the natal cleft, that mimicked individual cases of a verrucous type of porokerato- psoriasis. This entity, though unusual, is not sis of Mibelli that was localized to the natal cleft unique. Two similar cases of verrucous poroker- region. We report a similar case of verrucous poro- atosis of Mibelli limited to the natal cleft region keratosis of Mibelli limited to the natal cleft that and resembling psoriasis have been repor ted in the British literature. Verrucous porokeratosis ofMibelli localized to the natal cleft appears to be Case Report
a distinct clinical entity that can mimic psoriasis. A 44-year-old Asian man presented with a 28-year Better recognition of this for m of porokeratosis of history of pruritic plaques on the buttocks. These Mibelli may result in earlier diagnosis and initia- plaques had been gradually enlarging. The patient had seen several dermatologists and undergone various treatments for psoriasis, including topicalsteroids, coal tar, calcipotriene, tazarotene, psoralen-UVA, and topical tacrolimus, all of which were Porokeratosis is a heterogeneous group of dis- unsuccessful. He had a history of essential hyper- orders inherited in an autosomal-dominant tension and glaucoma but was otherwise healthy.
fashion and characterized histologically by the His medications included losartan, hydrochloro- presence of a cornoid lamella. The plaque type, thiazide, triamterene, and brimonidine eyedrops.
termed porokeratosis of Mibelli, has a predilection Family history of skin disease included only atopic for the acral areas and perigenital region. Poroker- dermatitis. Results from a review of systems were atosis of Mibelli is characterized clinically by one or more plaques, with a prominent raised border On physical examination, several well-demarcated, cleaved by a central furrow. The center of the scaly, red-brown, verrucous plaques with hyper- plaque is often atrophic, hairless, and either hyper- pigmented raised borders distributed bilaterally on pigmented or hypopigmented. However, lesions the buttocks (Figure 1) were noted. No other cuta- can be psoriasiform or verrucous, with varying neous lesions were evident, and there was no degrees of hyperkeratosis. The lesions begin as Two biopsies were obtained. The first, a 4-mm Accepted for publication May 8, 2003.
punch biopsy of the center of a plaque, demon- From the Department of Dermatology, University of Colorado strated psoriasiform hyperplasia of the epidermis with focal parakeratosis suggestive of a cornoid The authors report no conflict of interest.
lamella. The second, a 6-mm punch biopsy of the Reprints: Sylvia L. Brice, MD, Department of Dermatology, border of a plaque, revealed a thin column of University of Colorado Health Sciences Center, Anchutz CancerPavilion, PO Box 6510, Mail Stop F703, Aurora, CO 80010 parakeratotic cells with underlying absence of the granular layer and dyskeratotic and vacuolated Figure 1. Scaly verrucous
plaques with hyperpig-
mented raised borders
on the buttocks.
cells in the spinous layer, which is characteristic of 34-year-old man with a 9-year history of pruritic a cornoid lamella (Figure 2). Although there was dermatosis confined to the natal cleft. They deter- some psoriasiform hyperplasia, the rete ridges were mined this to be a novel form of porokeratosis, not club shaped, and no thinning of the suprapap- which they termed porokeratosis ptychotropica from illary plate or platelike parakeratosis and no collec- the Greek words ptyché (fold) and tropé (a turning).
tions of neutrophils in the epidermis or stratum In 1999, Stone et al2 described a 32-year-old man corneum were noted, as seen in psoriasis. This was with a 13-year history of pruritic dermatosis con- consistent with porokeratosis, making the diag- fined to the natal cleft, which they termed verrucous porokeratosis. As with our case, this second case also The patient underwent a trial of imiquimod had been mistaken for and treated as psoriasis. All cream applied once a day to one side of the but- 3 cases presented in young men and were intensely tocks and 5-fluorouracil cream applied twice a day pruritic, progressive, and confined to the natal cleft.
to the other side. The imiquimod cream caused As suggested in the previous case reports, this may severe irritation without much improvement and represent a distinct clinical variant of porokeratosis.
was discontinued. Subsequently, the 5-fluorouracil Porokeratosis is known to undergo malignant cream was applied to the entire lesion for transformation to Bowen disease, squamous cell 2 months, with resolution of the scaling and pruri- carcinoma, and basal cell carcinoma; the latest tus but with no decrease in the verrucous compo- review revealed at least 56 published cases.8 This nent or size of the plaques. After this therapy, review found that approximately 11% of patients treatment consisted of a trial of carbon dioxide with porokeratosis have lesions that undergo malig- (CO ) laser resurfacing on one side and dermabrasion nant transformation. Malignant transformation in on the other side. The porokeratosis recurred on porokeratosis has been associated with an over-the side treated with CO laser resurfacing. How- expression of p53.9-11 This potential for malignant ever, dermabrasion successfully removed the poro- transformation makes distinguishing porokeratosis keratosis, and, at the 6-month follow-up, no clinical evidence of porokeratosis in the dermabrasion- Treatment of porokeratosis has been largely anecdotal. There are isolated case reports of successful treatment using topical 5-fluorouracil (with and without occlusion), isotretinoin and Porokeratosis of Mibelli localized to the genital region alone is rare, with only 7 reported cases.1-7 dye laser radiation, grenz ray radiation, frequency- Two of these cases are clinically and histologically doubled Q-switched Nd:YAG laser radiation, identical to ours. In 1995, Lucker et al1 described a cryotherapy, dermabrasion, surgical excision, and Figure 2. Cornoid lamella
formation with the charac-
teristic slanted column of
coarse parakeratosis and
underlying loss of the
granular layer (H&E,
original magnification ϫ60).
electrodesiccation. In this case, topical 5-fluorouracil, 3. Levell NJ, Bewley AP, Levene GM. Porokeratosis of imiquimod cream, and CO laser resurfacing were Mibelli on the penis, scrotum and natal cleft. Clin Exp all ineffective in clearing the porokeratosis. How- ever, we found dermabrasion to be a potentially 4. Neri I, Marzaduri S, Passarini B, et al. Genital poroker- long-term and effective treatment for porokeratosis atosis of Mibelli. Genitourin Med. 1995;71:410-411.
5. Tangoren I, Weinberg JM, Ioffreda M, et al. Penile In summary, verrucous porokeratosis limited to porokeratosis of Mibelli. J Am Acad Dermatol.
the natal cleft appears to be a distinct clinical entity that may mimic localized psoriasis. Some of the 6. Trcka J, Pettke-Rank C, Brocker EB, et al. Genitoanocrural treatment modalities used for psoriasis are inappro- porokeratosis following chronic exposure to benzene. Clin priate and ineffective for porokeratosis (eg, UV light). However, unlike psoriasis, verrucous lesions 7. Robinson JB, Im DD, Jockle G, et al. Vulvar porokeratosis: of porokeratosis should be monitored for malignant case report and review of the literature. Int J Gynecol Pathol.
change because correct diagnosis is important for optimal patient care. This stresses the importance of 8. Otsuka F, Someya T, Ishibashi Y. Porokeratosis and malig- considering a biopsy in cases where the skin disease nant skin tumors. J Cancer Res Clin Oncol. 1991;117:55-60.
is not responsive to appropriate therapy.
9. Magee JW, McCalmont TH, LeBoit PE. Overexpression of p53 tumor suppressor protein in porokeratosis. ArchDermatol. 1994;130:187-190.
REFERENCES
10. Puig L, Alegre M, Costa I, et al. Overexpression of p53 in dis- 1. Lucker GP, Happle R, Steijlen PM. An unusual case of seminated superficial actinic porokeratosis with and without porokeratosis involving the natal cleft: porokeratosis malignant degeneration. Arch Dermatol. 1995;131:353-354.
ptychotropica? Br J Dermatol. 1995;132:150-151.
11. Sasaki S, Urano Y, Nakagawa K, et al. Linear porokerato- 2. Stone N, Ratnavel R, Wilkinson JD. Bilateral perianal sis with multiple squamous cell carcinomas: study of p53 inflammatory verrucous porokeratosis (porokeratosis expression in porokeratosis and squamous cell carcino- ptychotropica). Br J Dermatol. 1999;140:553-555.
mas. Br J Dermatol. 1996;134:1151-1153.

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