diagnosis. Gentle curettage followed by dermoscopy has the
potential to overcome this ﬂaw in the reasoning process, avoid-
ing missing a rare diagnosis.
* F. Zambito Spadaro,
Department of Surgical, Medical, Dental and Morphological Sciences
with Interest Transplant, Oncological and Regenerative Medicine,
Dermatology Unit, University of Modena and Reggio Emilia, Modena, Italy,
Department of Dermatology, University of Parma, Parma, Italy,
Dermopatico dell’Immacolata, Fondazione Luigi Maria Monti IRCCS,
Division of Dermatology, UO Multizonale ‘Santa Chiara’
Hospital, Trento, Italy
*Correspondence: F. Peccerillo. E-mail: email@example.com
†Both authors contributed equally to this work.
Honorarium, grant or other form of payment was not given to anyone of
the authors to produce the manuscript. All authors made substantive intel-
lectual contributions to the published study, and each author listed on the
manuscript has seen and approved the submission of the manuscript.
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Porokeratosis ptychotropica: a
diagnostic and therapeutic
The porokeratoses are characterized by the formation of cor-
noid lamellae. Porokeratosis ptychotropica (PP) is a rare
form ﬁrst described by Lucker, where the dyskeratotic skin
changes are mainly located around the gluteal cleft or genital
A 56-year-old man presented with mildly pruritic symmetrical
hyperkeratotic brown plaques with subtle ﬁne scaling, and smal-
ler satellite plaques, affecting both buttocks and partially the
intergluteal cleft (
Fig. 1a). The plaque began a year before on the
right buttock, and a second plaque followed on the left. Treat-
ment with emollients, antifungals and topical steroids was
unsuccessful. He was otherwise healthy.
Histology revealed verrucous epidermal hyperplasia with
hyperkeratosis alternating with columns of parakeratosis or cor-
noid lamella consistent with PP (Fig. 1b).
Given the poor response reported and the potential for malig-
we decided to treat with ingenol mebutate
(IM). After promising results in a 5 9 5 cm area with the
500 mg/g gel (Picato
Pharma, Denmark), we trea-
ted the whole affected 10 9 20 cm area on the left buttock
(Fig. 1c). The expected pustular reaction was observed, but three
weeks after, only a partial response was evident (Fig. 1d). Given
the associated discomfort and the patient
s unwillingness to fur-
ther pursue aggressive treatments, oral isotretinoin and 5% sali-
cylic acid ointment, with close follow-up if suspicious areas were
to develop, were chosen. Moderate thinning and lack of symp-
toms allowed the patient to carry on his regular activities.
PP affects the gluteal cleft, buttocks and genitalia in a ‘butter-
ﬂy’ fashion with sparing of the anal mucosa.
It slowly progresses
through satellite lesions that grow and coalesce. Pruritus may be
mild to severe. Past medical history is unremarkable, and no pre-
disposing factors have been identiﬁed. Patients are commonly
misdiagnosed as psoriasis, warts, epidermal naevus, chronic ecze-
mas, dermatophytoses, candidiasis, among others.
with other forms of porokeratosis has been reported.
The histological difference between PP and other poroker-
atoses resides in the distribution of the cornoid lamellae. In PP,
Figure 1 (a) Symmetrical hyperkeratotic plaques on the buttocks.
(b) Verrucous epidermal hyperplasia with hyperkeratosis alternat-
ing with several columns of parakeratosis or cornoid lamella, origi-
nating from a shallow depression of the epidermis where several
dyskeratotic keratinocytes were found. (c) Pustular reaction after
the application of IM. d) Partial response observed with IM after 3
© 2017 European Academy of Dermatology and Venereology
2018, 32, e86–e121
Letters to the Editor