Recurrent Squamous Cell Carcinoma Arising Within a Linear Porokeratosis

February 2020 | Volume 19 | Issue 2 | Case Reports | 205 | Copyright © February 2020

Published online January 9, 2020

Amelia M. Abbott-Frey , Alexandra J. Coromilas , George W. Niedt , Jesse M. Lewin

Columbia University Department of Dermatology, New York, NY


Porokeratosis is a disorder of epidermal keratinization. There are several clinical variants of porokeratosis including porokeratosis of Mibelli, punctate porokeratosis, disseminated superficial porokeratosis, disseminated superficial actinic porokeratosis, porokeratosis plantaris palmaris et disseminate, and linear porokeratosis. Histologically these lesions are characterized by a cornoid lamella, which is a compact column of parakeratosis. Although porokeratosis has historically been viewed as a benign lesion, there is evidence that these lesions may demonstrate malignant transformation. Research suggests that malignant degeneration occurs in about 7.5-11% of porokeratoses, commonly presenting as Bowen’s disease, SCC, or basal cell carcinoma.1,2 The risk of malignancy is hypothesized to be related to abnormal DNA ploidy in cells of the cornoid lamella as well as aberration of the p53 protein.3

Linear porokeratosis (LP) is an uncommon form of porokeratosis that is typically congenital, though lesions may arise in adulthood. LP’s follow Blaschko lines and are most often unilateral; however, they can rarely be generalized.3 Of all variants of porokeratosis, LP carries the highest risk for malignant transformation, estimated to occur in up to 19% of cases.11Our patient’s lesion was clinically consistent with LP, which was confirmed histologically. She had multiple risk factors for malignant transformation including a large, long-standing lesion, and location on the extremity.3-4 Other known risk factors for malignant transformation include sun exposure, immunosuppression, and ionizing radiation.1,2,4,5 While there are a few cases in the literature of multiple squamous cell carcinomas arising within linear porokeratosis, to our knowledge this is the first case to present with recurrence of a malignancy treated six years prior. This case highlights the importance of regular monitoring and surveillance for malignant degeneration in patients with large and long-standing linear porokeratosis.


None of the authors have any conflicts of interest, financial, or otherwise.


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2. Maubec E, Duvilard P, Margulis A. Common skin cancers in porokeratosis. Br J Dermatol. 2005;152:1389–91.
3. Sertznig P, von Felbert V, Megahed M. Porokeratosis: present concepts. JEADV. 2012;26:404-412.
4. Otsuka F, Umebayashi Y, Watanabe S, Kawashima M, et al.Porokeratosis large skin lesions are susceptible to skin cancer development: histological and cytological explanation for the susceptibility. J Cancer Res Clin Oncol. 1993;119:295–400.
5. Bencini PL, Tarantino A, Grimalt R, Ponticelli C, et al. Porokeratosis and immunosuppression. Br J Dermatol. 1995;132:74–8.


Jesse M. Lewin MD