The Malignancy Potential of Porokeratosis: A Single-Center Retrospective Study

Abstract

Background Porokeratosis (PK) is a rare group of keratinization disorders. While the overall prognosis of PK is favorable, malignant transformation of PK to skin cancer has been reported in 6.9% to 11.6% of the cases. Prior estimates of malignant transformation of PK have been based on reviews of published cases, which introduces possible publication bias. We aim to eliminate this potential bias and quantify the characteristics, risk factors, and malignancy potential of PK. Methodology A single-center retrospective chart review of patients with a diagnosis of PK was conducted. Results In this study, 6.4% to 16.4% of histologically confirmed PK lesions demonstrated malignant transformation. A higher proportion of disseminated superficial actinic porokeratosis (DSAP) cases (as high as 29.3%) showed malignant transformation compared to PK of Mibelli (as high as 6.0%). Out of the two cases of linear PK, both demonstrated malignant transformation. Conclusions In summary, PKs are at risk for malignant transformation, and patients with DSAP and linear PK, in particular, should receive more long-term surveillance. Limitations of this study include the inability to control for confounding factors due to the retrospective nature and the small size of our cohort.

Keywords: basal cell carcinoma; malignant transformation; melanoma; non-melanoma skin cancer; porokeratosis; squamous cell carcinoma.

Figure 1. Flowchart of the patient selection process and patients’ demographic/clinical characteristics.

DSAP, disseminated superficial actinic porokeratosis; dx, diagnosis; LE, lower extremity; PK, porokeratosis; PM, porokeratosis of Mibelli; PPPD, porokeratosis palmaris, plantaris, et disseminata; UE, upper extremity * search terms used at this stage include “porokeratosis,” “disseminated superficial porokeratosis,” and “DSAP” ** search terms used at this stage include “skin cancer,” “NMSC,” “basal cell,” “squamous cell,” “Bowen,” “melanoma,” “MIS,” “BCC,” and “SCC.” The diagnosis of skin cancer was confirmed by reviewing histopathology reports