Dermoscopy of inflamed seborrheic keratosis: A great mimic of malignancy

• Published in: Australasian journal of dermatology 2022-02, Vol.63 (1), p.53-61
• Main Authors: Álvarez‐Salafranca, Marcial, Gómez‐Martín, Ignacio, Bañuls, José, Serrano, Patricia, Medina, Carolina, Llambrich, Alex, Pizarro, Ángel, Ara, Mariano, Zaballos, Pedro
• Format: Article
• Language: English
• Subjects: Basal cell carcinoma; Biopsy; Cancer; Clinical Competence; Dermatologists; Dermatology; dermatoscopy; Dermoscopy; Diagnosis; Diagnosis, Differential; Humans; Inflammation; Internship and Residency; Keratosis; Keratosis, Seborrheic - pathology; Malignancy; malignant melanoma; Melanoma; Nevus; Retrospective Studies; seborrheic keratosis; Skin Neoplasms; Squamous cell carcinoma; Tumors; Vascularization
• ISSN: 0004-8380; 1440-0960
• DOI: 10.1111/ajd.13781

Background Clinical and dermoscopic recognition of seborrheic keratoses (SKs) is often straightforward, and biopsy might not be required. However, inflamed SKs (iSKs) can pose a diagnostic challenge. Dermoscopic features of iSKs have not yet been evaluated to date. Objectives To assess the diagnostic ability of a group of dermatologists to diagnose iSKs by dermoscopy. To evaluate the dermoscopic findings of a long series of inflamed seborrheic keratoses. Methods Clinical and dermoscopic images of 100 difficult‐to‐diagnose skin tumours, including 29 iSKs, were presented to 33 clinicians (24 dermatologists and 9 dermatology residents), who were blinded to the diagnosis. The dermoscopic features of a series of 219 iSKs were retrospectively analysed. Results iSKs were correctly identified in a 37.6% of cases. Classic dermoscopic criteria were present in only 47% of iSKs. The most frequent dermoscopic feature in iSKs was the presence of vascularization (91.3%), but only a 44.5% showed predominance of hairpin vessels. A bluish hue was observed in 18.3% of lesions. Seven dermoscopic patterns were identified, based on the dermoscopic similarity to other tumours: seborrheic keratosis‐like (28.8%); squamous cell carcinoma‐like (25.6%); melanoma‐like (17.8%); keratoacanthoma‐like (6.8%); basal cell carcinoma‐like (5.9%); verruca vulgaris‐like (5.9%); nevus‐like (2.3%). Conclusions The diagnosis of iSKs can be challenging even with dermoscopy. They may behave as authentic mimics of other cutaneous tumours, including squamous cell carcinoma or melanoma. For this reason, histopathological examination should be mandatory in these cases.