Keratoacanthoma: Clinical, Dermoscopic, and Histopathological Features in a Prospective Case Series of 11 Patients and Literature Review

Abstract

Background: Keratoacanthoma (KA) may be difficult to distinguish from well-differentiated cutaneous squamous cell carcinoma because their clinical, dermoscopic, and histopathological features overlap. Aims: The study aims to describe the clinical, dermoscopic, and histopathological features of keratoacanthoma (KA) in a North African population and to compare them with published data. Study design: Prospective, single-centre, descriptive case series. Place and Duration of Study: Department of Dermatology and Venereology, Ibn Sina University Hospital, Rabat, Morocco, from June 2021 to May 2023. Methodology: All consecutive patients with a clinical and/or histopathological diagnosis of KA who underwent dermoscopic evaluation (DermLite DL4) were included. Clinical variables (age, sex, phototype, location, size, duration, and relevant history) were recorded using a standardised form and summarised in Table 1. Dermoscopic features (central amorphous keratin zone, white circles, white scales, erythema, and peripheral vascular patterns) were systematically assessed and tabulated in Table 2. Definitive diagnosis was based on complete excision and histopathology whenever feasible; in two patients, KA was diagnosed on the basis of a highly characteristic clinical-evolutionary course with documented spontaneous regression. Results: Eleven patients (seven females and four males; mean age, 60.8 years) were included. Fitzpatrick phototypes III–IV predominated (9/11), and the upper extremities were the most common sites (6/11). Mean lesion size was 2.1 cm, and mean duration was 6.1 months. The most frequent dermoscopic findings were a central amorphous keratin zone (8/11), erythema (7/11), white circles (5/11), white scales (5/11), and polymorphous peripheral vascular patterns, including hairpin (4/11), linear irregular (5/11), arborising (4/11), and dotted/glomerular vessels (3/11), arranged in a crown-like distribution around the central keratin mass. Nine patients underwent complete excision with histopathological confirmation of KA, and two showed documented spontaneous regression. Conclusion: KA remains a diagnostic challenge because of its overlap with well-differentiated cutaneous squamous cell carcinoma. The polymorphous dermoscopic vascular pattern and the predominance of phototypes III–IV in this North African series highlight features that should not be overlooked in darker skin types. An integrated clinicodermoscopic-histopathological approach remains essential for accurate diagnosis.