PA02 Spitz melanocytoma: the case for a common language

Abstract

Establishing diagnoses along the pathway of Spitz naevus to Spitz melanoma remains challenging, with atypical Spitz naevi (ASN) representing a broad spectrum of intermediate lesions between the two. Diagnosis of ASN relies on assessment of histological, immunohistochemical, molecular and clinical features, rather than clear diagnostic criteria. Although the metastatic risk is low, it exceeds that of benign naevi, making consistency in diagnosis and communication essential. We present an evolving case series of eight paediatric patients diagnosed with ASN within a tertiary paediatric dermatology service over a 29-month period. Marked variation in terminology was identified: diagnoses included Spitz melanocytoma (n = 1); mixed terminology (n = 5) including combinations of ASN, Spitz melanocytoma, atypical Spitz tumour, spitzoid melanocytoma, Spitzoid melanocytoma and intermediate melanocytic tumour; ASN (n = 1) and atypical spitz tumour (n = 1). Risk was explicitly documented in only five cases. In half of the cases, the terminology used in patient discussions differed from the final histological diagnosis. The WHO Classification of Skin Tumours (5th edition) recognizes Spitz melanocytoma as the intermediate lesion within the pathway. MPATH-Dx version 2.0 presents a four-tiered risk-based framework. Most intermediate lesions will fall within their class II, stratified as a low risk of progression to invasive melanoma (1 in every 100–1000 lesions). We propose that education and consistent terminology are important. Although the WHO-recommended terminology includes multiple terms, for clinicians the single use of Spitz melanocytoma brings clarity. Histological reporting should include a clear final conclusion using the recognized risk stratification system MPATH-Dx version 2.0. Cases should be discussed in a skin cancer multidisciplinary meeting. We would also suggest a standardized patient information leaflet explaining the Spitz spectrum and terminology to be used. We advocate for a standardized approach locally, aiming for broader UK-wide consensus.