Bowenoid transformation in seborrheic keratosis: A retrospective analysis of 429 patients

Seborrheic keratosis is a common, benign skin tumor. Numerous reports have shown its possibility of malignant transformation. This study was designed to demonstrate the occurrence of concomitant seborrheic keratosis and skin cancers.

Data was retrospectively reviewed from all patients with a diagnosis of seborrheic keratosis in pathology department of Alzahra Hospital and a private pathology laboratory in Isfahan, Iran over a 4-year period. We classified all demographic data and associated dysplasia or Bowen's disease and analyzed them by student-t or chi-square tests.

From all 429 specimens, 5 (1.2%) were found to be associated with Bowen's disease and one (0.2%) with mild dysplasia in squamous epithelium. All cases arose within the clinically, atypical seborrheic keratosis. More men were affected with lesions alone and with malignancy (230/423 (54.4%) and 5/6 (83.3%), respectively) compared to women. The average age of patients suffering from lesions with and without associated malignancy was 57 and 54 years, respectively. The common site of lesion alone was head and neck but lesions with malignancy involved lower extremities. The two lesions were significantly different in site of occurrence (p < 0.001).

Generally, although the association between seborrheic keratosis and skin malignancy appears to be accidental, it must always be in mind. Therefore, histopathologic examination of all seborrheic keratosis should be considered, especially when seborrheic keratosis has atypical clinical manifestations.