DP05 Diagnostic value of nailbed biopsy in assessment of pigmented nail lesions: a multicentre audit study over 20 years
Year: 2025
Type: conference-abstract
Abstract: The aim of this study is to assess the diagnostic yield of nailbed biopsies taken for pigmented nail conditions. The data were collected from two main hospitals in London and all samples were processed in the same histopathology laboratory. Free search of ‘nail bed’ on the reporting platform was used and the clinical details were also reviewed from the patients’ medical records. In total 176 biopsies were reviewed, 74 of which included a pigmented lesion in the differential diagnosis (melanonychia). Overall, 33 of 74 patients (45%) had a diagnosis of normal tissue by well-experienced dermatopathologists despite the clinical diagnosis of melanonychia. The patients’ age range was 24–81 years (average 50); 19 were female and 13 male; and biopsy sizes ranged from 2 × 2 × 1 mm to 8 × 3 × 3 mm. Two biopsies were orientated by the dermatologist. Four (12%) were labelled as inadequate. Masson–Fontana stain with or without melan-A and SOX-10 immunohistochemical stains was used in most cases, and multiple levels were examined, including levels through the block. Most request forms had good clinical history and some also included explanatory diagrams. Despite the adequate sizes of the biopsies, the low diagnostic rate of 66% reflects the discrepancy between the clinical and pathological diagnoses. This may be related to either the subtle dyschromia of the lesion or detachment of surface epithelium. Melanocytic activation may be subtle and it may not be possible to compare it with the normal colour of adjacent tissue (normal control). The accuracy of clinical sampling is difficult to assess. There is also inconsistency in the orientation of the nailbed during the embedding process as it may be cut vertically, parallel or at an angle to the plane of pigmentation. In conclusion, despite the adequate size of the nailbed biopsies, the diagnostic value for dyschromia and melanocytic lesions remains low (66% in our series). Some explanations for this may include inaccurate or inadequate sampling of the lesion, lack of correlation with clinical findings and dermoscopic photographs, and lack of orientation or suboptimal embedding of the punch biopsy in the laboratory. We recommend adequate lesion sampling and avoiding blind punch biopsy procedure, careful review of clinical features and photographs, clear orientation of the surface of all nailbed biopsy samples by the dermatologist (such as proximal or distal surface inking), embedding by trained senior laboratory staff, and cutting unstained slides between the levels for special stains in order to increase the diagnostic yield.
Source: British Journal of Dermatology
Authors: Faris Kubba, Haya Alani
Language: English
Topic: Nail Diseases and Treatments
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W4411732635