PSD03 Isolated genital angiokeratomas: an under-recognized cutaneous marker of Fabry disease revealed by dermoscopy

Abstract

Fabry disease (FD), an X-linked lysosomal storage disorder, classically presents with angiokeratomas in the bathing trunk distribution. Isolated genital presentations, frequently misdiagnosed as condylomata, represent an underestimated diagnostic pitfall. This case demonstrates the pivotal role of dermoscopy in establishing a presumptive diagnosis when genetic or biochemical testing is unavailable. This is particularly relevant in resource-limited settings where FD remains underdiagnosed. A 32-year-old man with no personal or family medical history presented with asymptomatic genital papules evolving over 6 months, initially diagnosed as condylomata. Clinical examination revealed well-demarcated violaceous lesions localized exclusively on the penile shaft. Dermoscopic analysis demonstrated homogeneous dark-red lacunae separated by whitish-yellow septa, forming a vascular honeycomb pattern. No verrucous structures (dotted vessels, mosaic pattern) or associated mucosal lesions were observed. The patient denied acroparaesthesia, hypohidrosis or family history of FD. This case raises three scientifically significant issues. Firstly, dermoscopy serves as a diagnostic pivot: the combined pattern of red lacunae with pale septa demonstrates high specificity for Fabry angiokeratomas, distinguishing them from condylomata (comma-shaped or dotted vessels) and lichen sclerosus (homogeneous whitening). This visual signature provides a robust alternative when molecular testing is inaccessible. Secondly, recognition of oligosymptomatic forms is crucial: isolated genital angiokeratomas represent an emerging FD phenotype, often associated with residual α-galactosidase A mutations. Absence of systemic symptoms does not exclude silent visceral involvement, justifying proactive screening. Thirdly, an adapted surveillance strategy is recommended: we propose a monitoring algorithm including quarterly dermoscopic surveillance to detect lesion extension, annual screening for renal complications (urinalysis for albuminuria) and cardiac abnormalities (electrocardio­gram), and extended family investigation, as 40% of index cases reveal previously unrecognized family history. Isolated genital angiokeratomas must be integrated into the differential diagnoses of genital lesions, even without systemic signs. Dermoscopy, through its high specificity and accessibility, constitutes a first-line tool for identifying these cutaneous markers of FD.