Indian Journal of Dermatology
  Publication of IADVL, WB
  Official organ of AADV
Indexed with Science Citation Index (E) , Web of Science and PubMed
Users online: 1212  
Home About  Editorial Board  Current Issue Archives Online Early Coming Soon Guidelines Subscriptions  e-Alerts    Login  
    Small font sizeDefault font sizeIncrease font size Print this page Email this page

Table of Contents 
Year : 2022  |  Volume : 67  |  Issue : 6  |  Page : 744-746
Porokeratosis ptychotropica: A rare manifestation and dermoscopic feature

From the Department of Dermatology, Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine, Zhejiang, China

Date of Web Publication23-Feb-2023

Correspondence Address:
Shan Zhang
Department of Dermatology, Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine, Zhejiang - 325000
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijd.ijd_1145_20

Rights and Permissions


We report a case of porokeratosis ptychotropica with a rare manifestation. Dermoscopy showed dotted vessels, cerebriform pattern, white scales, and brown and greyish white tracks in the periphery over a red-brown background. A skin biopsy confirmed the diagnosis from the presence of cornoid lamellae.

Keywords: Cornoid lamellae, dermoscopy, porokeratosis ptychotropica

How to cite this article:
Zhang S. Porokeratosis ptychotropica: A rare manifestation and dermoscopic feature. Indian J Dermatol 2022;67:744-6

How to cite this URL:
Zhang S. Porokeratosis ptychotropica: A rare manifestation and dermoscopic feature. Indian J Dermatol [serial online] 2022 [cited 2023 Mar 29];67:744-6. Available from:

   Introduction Top

Porokeratosis refers to a group of keratinisation disorders characterized by lesions with keratotic borders corresponding to cornoid lamella in histology. Porokeratosis ptychotropica is a rare form of porokeratosis. Diagnosis is often delayed for many years due to the polymorphic presentation of the lesions. Here, we present a rare manifestation of porokeratosis ptychotropica.

   Case Report Top

A 55-year-old Chinese man presented with a 10-year history of pruritic rash over the bilateral buttocks. The lesions started appearing as sporadic, pink-to-red, bean-sized papules and later coalesced into verrucous plaques with severe itching, especially in hot climate or during perspiration. Treatment with topical tretinoin cream and urea cream was unresponsive. The patient was otherwise healthy. No significant medical or family history was present.

Physical examination showed multiple red-to-violaceous, well-demarcated, verrucous papules and plaques on the buttocks and extending to the upper thighs symmetrically, accompanied by discrete satellite lesions at the periphery [Figure 1]. Subtle hyperkeratosis could be seen on some lesions.
Figure 1: Multiple red-to-violaceous, well-demarcated, subtle hyperkeratosis, verrucous papules and plaques on the buttocks and upper thighs symmetrically, with discrete satellite lesions at the periphery (a and b)

Click here to view

Dermoscopic examination exhibited the presence of a brown track with greyish white tracks inside and outside of the track in the periphery [Figure 2]. A few red dotted vessels, cerebriform pattern, and white scales could be seen at the centre over a red-brown background. A punch biopsy of a classic papule on the left buttock revealed epidermal hyperkeratosis, multiple digitate epidermis with columns of parakeratosis in the form of prominent cornoid lamellae, an absent granular layer, acanthosis, and some dyskeratotic keratinocytes [Figure 3]. There was a perivascular lymphocytic inflammatory infiltration and pigment dropout in papillary dermis.
Figure 2: Dermoscopic figure dotted vessels (white circle), cerebriform pattern (black circle), white scales (white arrow), and brown and greyish white tracks at the periphery (black arrow) (× 10, polarized mode, Heine Delta 20T dermatoscope)

Click here to view
Figure 3: Histopathology: Epidermal hyperkeratosis, a digitate epidermis with columns of parakeratosis in the form of prominent cornoid lamellae (black arrow), an absent granular layer, acanthosis, and some dyskeratotic keratinocytes (H and E × 40) (a). Multiple cornoid lamellae (black arrow), a perivascular lymphocytic inflammatory infiltration and pigment dropout in papillary dermis (H and E × 40) (b)

Click here to view

Based on these findings, the diagnosis of porokeratosis ptychotropica was made. The patient subsequently underwent treatment with oral acitretin 30 mg/d, topical tretinoin cream, and urea cream for two months with little improvement.

   Discussion Top

Porokeratosis ptychotropica was first reported in 1995 by Lucker et al.[1] and was described as a rare variant of porokeratosis involving body folds, particularly the intergluteal cleft. The concept of this entity later evolved and now refers to the eruption composed of symmetrical pruritic verrucous, hyperkeratotic or psoriasiform lesions localised to the perinatal cleft, buttocks, upper thighs, and the genitalia in a butterfly fashion with peripheral satellite lesions. The growth is often slow. Porokeratosis ptychotropica mainly affects immunocompetent middle-aged men, or rarely immunocompromised old women.[2],[3] The aetiology and pathogenesis of porokeratosis ptychotropica still remains unclear. Family history is often negative. Only one familial case of two brothers was reported by Takiguchi RH et al.[4] It can coexist with other types of porokeratosis, including porokeratosis of Mibelli,[5] linear porokeratosis, and disseminated superficial actinic porokeratosis.[3] A similar mechanism may exist. To note, there are multiple alternative descriptions in published literatures of porokeratosis ptychotropica, such as hyperkeratotic porokeratosis, genitogluteal porokeratosis, verrucous porokeratosis, and seborrheic keratosis-like porokeratosis. These terminologies are not uniform and some might be a subset of porokeratosis of Mibelli.

Cornoid lamellae, a diminished or absent granular layer, as well as dyskeratotic cells are characteristic histological features of porokeratosis. Some authors suggest that multiple cornoid lamellae throughout the lesion is a classic feature of porokeratosis ptychotropica. But this histological finding did not show in the case of porokeratosis ptychotropica in psoriasis form,[6] and other types of porokeratosis with verrucous appearance could also reveal multiple cornoid lamellae.[3],[7] As a result, we propose that the number and distribution of cornoid lamellae are more relative with the morphology of the lesions rather than the type. Other histological findings including vacuolated basal layer, inflammatory infiltration in the dermis, incontinence of pigment, and dilated papillary dermal blood vessels can also be found in some cases. Besides, the histology of central lesions might be nonspecific, so the periphery seems to be the ideal location for biopsy if the diagnosis of porokeratosis is considered.[6],[8] In our case, though it was a rare manifestation presenting as a red-to-violaceous papular form with little scales, we still classified it as porokeratosis ptychotropica according to the hereditary trait, onset age, sex, the classical symptom of pruritus, distribution of lesions, and the histopathological feature of cornoid lamellae.

Dermoscopic examination can be used for differential diagnosis and early detection of malignant transformation. The dermoscopic description of porokeratosis ptychotropica has been seldom reported, and it is somewhat different from our case: the rosette sign and central scar-like area could be found.[9] In our case, it should be differentiated from verruca, seborrheic keratosis, and lichen planus. In dermoscopy, verruca generally presents as “even-colored light brown to yellow patch with dots or globular vessels”.[10] Typical findings like comedo-like openings, milia-like cysts, and hairpin vessels can be seen in seborrheic keratosis. Wickham striae is specific for lichen planus. As for our case, the hyperkeratotic border, the hallmark of porokeratosis, clinically indistinguishable and appearing as peripheral brown and greyish white tracks in dermoscopy, can make a difference and guide the bioptic sampling.

The therapy of porokeratosis is usually refractory and easy to relapse. Conventional treatments including oral and topical retinoids, vitamin D analogues, corticosteroids, 5-fluorouracil, 5% imiquimod, and cryotherapy showed minimal or variable effects. Surgery seems to be the only method that leads to a satisfactory result, but it is not advisable in extensive lesions like porokeratosis ptychotropica. Recently, Fustà-Novell et al.[11] reported the application of photodynamic therapy in porokeratosis ptychotropica with symptomatic relief and clinical improvement: this seems to be a promising therapeutic option. In view of the risk of malignant transformation,[2] early detection and long-term follow-up are still necessary.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


Thanks are due to Deren Fang from Department of Dermatology, The First Affiliated Hospital, College of Medicine, Zhejiang University for offering the partial clinical data of the patient.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Lucker GP, Happle R, Steijlen PM. An unusual case of porokeratosis involving the natal cleft: Porokeratosis ptychotropica? Br J Dermatol 1995;132:150-1.  Back to cited text no. 1
Mazori DR, Shvartsbeyn M, Meehan SA, Tarsis SL. Transformation of porokeratosis ptychotropica into invasive squamous cell carcinoma. Int J Dermatol 2017;56:679-80.  Back to cited text no. 2
Murase J, Gilliam AC. Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: Update on the genetics and clinical expression of porokeratosis. J A Acad Dermatol 2010;63:886-91.  Back to cited text no. 3
Takiguchi RH, White KP, White CR Jr, Simpson EL. Verrucous porokeratosis of the gluteal cleft (porokeratosis ptychotropica): A rare disorder easily misdiagnosed. J Cutan Pathol 2010;37:802-7.  Back to cited text no. 4
Ma Y, Li C, Wu J, Cui P, Lin L, Feng S. Coexistence of porokeratosis ptychotropica with porokeratosis of Mibelli in a Chinese man. Postepy Dermatol Alergol 2015;32:307-9.  Back to cited text no. 5
Kawakami Y, Mitsui S. A case of porokeratosis ptychotropica: Successful treatment with topical 5% imiquimod cream. Clin Exp Dermatol 2017;42:839-41.  Back to cited text no. 6
Caseiro Silverio P, Pham XC, Kaya G. Porokeratoma: A possible association with human papillomavirus infection. Dermatopathology (Basel) 2015;2:43-5.  Back to cited text no. 7
Malek J, Chedraoui A, Kibbi AG, Ghosn S. Genitogluteal porokeratosis: 10 Years to make the diagnosis! Am J Dermatopathol 2009;31:604-6.  Back to cited text no. 8
Luo Y, Liu J. Image Gallery: Verrucous porokeratosis with characteristic histopathological and dermoscopic features. Br J Dermatol 2017;176:e38.  Back to cited text no. 9
Kim WJ, Lee MK, Song M, et al. Clinical clues for differential diagnosis between verruca plana and verruca plana-like seborrheic keratosis. J Dermatol 2015;42:373-7.  Back to cited text no. 10
Fustà-Novell X, Podlipnik S, Combalia A, Morgado-Carrasco D, Ferrando J, Mascaró JM Jr, et al. Porokeratosis ptychotropica responding to photodynamic therapy: An alternative treatment for a refractory disease. Photodermatol Photoimmunol Photomed 2017;33:271-4.  Back to cited text no. 11


  [Figure 1], [Figure 2], [Figure 3]


Print this article  Email this article
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Article in PDF (923 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  

   Case Report
    Article Figures

 Article Access Statistics
    PDF Downloaded18    
    Comments [Add]    

Recommend this journal