[Dysplastic nevi: difficulties in diagnosis]

Dysplastic nevus is one of the most common tumors in the practice of a dermatologist and pathologist. However, despite this and the presence of a large number of published studies, since the late 1970s and to this day, the diagnosis and treatment of dysplastic nevi have been controversial.

To determine the accuracy and reproducibility of morphological findings in the group of dysplastic nevi.

A total of 178 skin resection specimens for 2023 were used in our study, which can be conditionally divided into three groups according to the correct clinical diagnosis: (1) with suspected dysplastic nevus/melanoma - 56% (99/178), (2) dysplastic nevus - 35% (62/178), (3) without dysplastic nevus/melanoma - 9% (7/178). Of the 178 observations, 31 cases were selected for further review. The selection criteria were the following morphological findings: (1) DN with moderate/severe atypia, (2) DN with any degree of atypia without clinical suspicion for it, (3) melanoma without clinical suspicion for it. Agreement between pathology reports and the original diagnosis was measured by the proportion of the same reports in the same educational category, using Wilson 95% confidence interval.

There were 72 dysplastic nevi after first pathology report: 77.8% (56/72) with mild atypia, 18.1% (13/72) with moderate atypia, 4.2% (3/72) with severe atypia. The agreement between the clinical and primary morphological diagnoses was 58.4% (104/178), and in the dysplastic nevus group - 40.3% (25/62). When reviewing the 31 cases, the percentage of agreement for a simple nevus was 100%, for dysplastic with mild atypia - 70.8%, for dysplastic nevus with severe atypia - 33.3%, for melanoma - 48.4%. The coincidence of the initial and repeated diagnoses was 54.8% (14/31), 51.6% (16/31) and 29.0% (9/31) for each of the doctors.

Our study revealed low accuracy and reproducibility of morphological conclusions in the group of dysplastic nevi. The determination of similar lesions by different pathologists and deviations from the initial diagnoses can primarily be explained by insufficiently reproducible diagnostic criteria.