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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

Abstract
Here we report a case of linear porokeratosis with recurrent malignant degeneration to squamous cell carcinoma (SCC) recurring six years after excision of initial SCC. A 79-year-old woman presented with a friable tumor located within a longstanding lesion on her posterior thigh. Six years prior, she was diagnosed with SCC arising within the same lesion, which had been surgically excised with negative margins. Physical examination revealed a 3.5 x 2.7 cm friable tumor on the left proximal posterior thigh. The tumor was located within a hyperpigmented and erythematous scaly linear plaque within a line of Blaschko, extending from the left buttock to the left distal posterior thigh. Two 4 mm punch biopsies were performed: one of the erythematous plaque on the left buttock and one from the friable tumor on the left posteromedial thigh. Histology from the left buttock revealed a cornoid lamella consistent with porokeratosis and the left posteromedial thigh revealed SCC. The patient underwent Mohs micrographic surgery with negative margins, followed by a linear repair. Porokeratosis is a disorder of epidermal keratinization that has been associated with malignant degeneration, although such cases are rare. The risk of recurrence of SCC arising within a porokeratosis is unknown. This case emphasizes the importance of ongoing monitoring for malignant degeneration within these lesions.

J Drugs Dermatol. 2020;19(2)205-206 doi:10.36849/JDD.2020.4640

CASE REPORT

A 79-year-old woman with a history of hypertension and hypothyroidism presented with a friable tumor within a lesion on the left buttock and posterior thigh which has been present for her entire life. She was diagnosed with squamous cell carcinoma (SCC) arising within the linear plaque six years prior, which was surgically excised with negative margins. Physical examination revealed a hyperpigmented and erythematous scaly linear plaque within a line of Blaschko, extending from the left buttock to the left distal posterior thigh (Figure 1). There was a 3.5 x 2.7 cm friable tumor on the proximal posterior thigh within the linear plaque.




Two 4 mm punch biopsies were performed: one of the erythematous plaque on the left buttock and one from the friable tumor on the left posteromedial thigh. Histology revealed a cornoid lamella consistent with porokeratosis on the left buttock (Figure 2) along with SCC in situ (Figures 3 and 4) on the posteromedial thigh. The patient subsequently underwent 1 stage of Mohs micrographic surgery with complete tumor extirpation, followed by a linear repair.