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A rare variant of porokeratosis: Porokeratosis ptychotropica

2006; Elsevier BV; Volume: 55; Issue: 5 Linguagem: Inglês

10.1016/j.jaad.2005.12.009

1097-6787

Dong Kyung Lee, Sang Hyun Oh, Sung Eun Chang, Mi Woo Lee, Jee Ho Choi, Kee Chan Moon, Jai Kyoung Koh,

Dermatological and Skeletal Disorders

To the Editor: Porokeratosis is a disorder of epidermal keratinization characterized by an extending keratotic lesion with an atrophic center and a prominent peripheral ridge. Histologically, a cornoid lamella is a pathognomonic feature. Clinically, 5 variants are commonly recognized: classic porokeratosis Mibelli, disseminated superficial porokeratosis, porokeratosis palmaris et plantaris disseminata, linear porokeratosis, and punctate porokeratosis.1Wolff-Schreiner E.C. Porokeratosis.in: Freedberg I.M. Eisen A.Z. Wolff K. Austen K.F. Goldsmith L.A. Katz S.I. Fitzpatrick's dermatology in general medicine. 6th ed. McGraw-Hill, New York2003: 532-537Google Scholar We report a rare case of porokeratosis confined to the perianal area and toe of the left foot. A 50-year-old man presented with pruritic lesions in the perianal area and on the left foot of 4 years' duration; these had started as a few erythematous keratotic papules. They gradually coalesced to form more extensive keratotic plaques on the buttocks. New satellite lesions continued to appear at the periphery of the plaque. He had no previous history of medication or skin diseases and was otherwise in good health. There was no family history of similar skin lesions. Skin examination revealed multiple reddish brown hyperkeratotic papules and plaques symmetrically affecting both buttocks, and similar lesions affecting the toes and toewebs of the left foot (Fig 1). Histology of skin biopsy specimens from the buttock and left foot revealed similar features: acanthosis, orthohyperkeratosis, and multiple cornoid lamellae, a histopathologic hallmark of porokeratosis. Beneath the cornoid lamella, the granular layer was absent, and there existed some dyskeratotic cells. Focal degenerative change of the basal layer was present under the cornoid lamella. In the papillary dermis, there were nonspecific mononuclear cell infiltrates and prominent eosinophilic amorphous globular materials stained with periodic acid–Schiff/diastase and anticytokeratin antibody (Zymed, AE1/AE3) (Fig 2). On the basis of clinical and histologic findings, the possibility of other dermatoses including perianal psoriasis, inflammatory linear verrucous epidermal nevus, lichen simplex chronicus, various forms of Blaschko linear dermatoses, and hyperkeratosis lenticularis perstans were excluded. A diagnosis of porokeratosis ptychotropica with dermal amyloid deposits was made. Although treated with carbon dioxide laser and 3 sessions of cryotherapy, the lesions did not show satisfactory improvement.Fig 2A, Specimen from buttock. Cornoid lamellae, some dyskeratotic keratinocytes, and focal degenerative change of basal layer. B, Amorphous globular material in papillary dermis positively stained with anticytokeratin antibody. (A, Hematoxylin-eosin stain; B, Zymed, AE1/AE3; A and B, original magnification: ×100.)View Large Image Figure ViewerDownload (PPT) This patient's lesion differed from the 5 well-known clinical variants of porokeratosis. In 1995, Lucker, Happle, and Steijlen2Lucker G.P.H. Happle R. Steijlen P.M. An unusual case of porokeratosis involving the natal cleft: porokeratosis ptychotropica?.Br J Dermatol. 1995; 132: 150-151Crossref PubMed Scopus (76) Google Scholar first described a case very similar to ours. They proposed the designation “porokeratosis ptychotropica” to distinguish it from the more common variants of porokeratosis. The term “ptychotropica” is derived from the Greek words ptyche (fold) and trope (a turning). Thereafter, two other similar cases were reported.3Stone N. Ratnavel R. Wilkinson J.D. Bilateral perianal inflammatory verrucous porokeratosis (porokeratosis ptychotropica).Br J Dermatol. 1999; 140: 538-568Crossref PubMed Scopus (9) Google Scholar, 4Jee M.S. Chang S.E. Suh H.S. Choi J.H. Sung K.J. Moon K.C. et al.Porokeratosis ptychotropica associated with dermal amyloid deposits.Clin Exp Dermatol. 2003; 28: 447-459Crossref PubMed Scopus (7) Google Scholar All of the previously reported cases had similar clinical and histologic features: perianal lesions affecting both buttocks symmetrically and conspicuous cornoid lamellae. Interestingly, our patient had also had multiple porokeratotic plaques confined to the toes of the left foot. The association between porokeratosis and amyloid deposits has rarely been reported, particularly in relation to several cases of disseminated superficial porokeratosis.5Anantea A. Giuliano M.C. Balus L. Disseminated superficial porokeratosis with dermal amyloid deposits.Am J Dermatopathol. 1998; 20: 86-88Crossref PubMed Scopus (27) Google Scholar, 6Kim J.H. Yim H. Kang W.H. Secondary cutaneous amyloidosis in disseminated superficial porokeratosis: a case report.J Korean Med Sci. 2000; 15: 478-481PubMed Google Scholar One recent study4Jee M.S. Chang S.E. Suh H.S. Choi J.H. Sung K.J. Moon K.C. et al.Porokeratosis ptychotropica associated with dermal amyloid deposits.Clin Exp Dermatol. 2003; 28: 447-459Crossref PubMed Scopus (7) Google Scholar showed the association of porokeratosis ptychotropica with dermal amyloid deposits, similar to the case we report. According to the immunohistochemical study results of our case, amyloid deposition appears to be related as follows: porokeratosis ptychotropica shows dyskeratotic epidermal cells and a focal basal layer degeneration that is more prominent under the cornoid lamella, and the dermal amyloid deposits were likely to have occurred through the epidermal defect.