Enhancing Diagnosis of Flat Pigmented Basal Cell Carcinoma with Line-Field Confocal Optical Coherence Tomography

Line-field confocal optical coherence tomography (LC-OCT) is a novel noninvasive imaging technique that combines the depth resolution of optical coherence tomography with the cellular detail of reflectance confocal microscopy, allowing real-time, high-resolution imaging of the skin. We report an 84-year-old male with a flat, pigmented macule on the nasal dorsum, gradually darkening over two years. Clinically, the lesion measured 7 mm with irregular but well-defined borders; dermoscopy showed rhomboidal structures, an annular granular pattern, white circles around a keratotic plug, and a solitary pigmented globule, suggestive but not diagnostic of malignancy. LC-OCT (Damae Medical, Paris, France) revealed sharply demarcated dermal lobules surrounded by a hyporeflective rim (“clefting”), an outer hyperreflective “bright rim,” and a millefeuille pattern within the lobules, consistent with basaloid proliferation. Histopathology after excision confirmed a pigmented basal cell carcinoma. Pigmented BCCs can mimic melanocytic lesions, and in such cases LC-OCT offers noninvasive architectural and cytologic details allowing recognition of hallmark features like lobular structures and peripheral clefting. Its integration with dermoscopy enhances diagnostic accuracy, supports timely management, and underscores the value of LC-OCT as a “virtual histology” tool in evaluating challenging pigmented lesions.