Summary Background Atypical Spitz tumours (ASTs) are regarded as an intermediate category distinguished from prototypical Spitz naevus by presenting one or more atypical features and often by an uncertain malignant potential. Clinical and dermoscopic features may play a relevant role in the diagnostic approach. Aim To evaluate the clinical and dermoscopic features of ASTs, and their evolution over time. Methods This was a descriptive, multicentre study of the clinical and dermoscopic characteristics of ASTs. Data on clinical and dermoscopic characteristics, histopathology, local extension, therapy and follow‐up, lymph node staging, complete lymph node dissection, and outcome were collected from the databases of four Italian Dermatology Units for the period 2004–2021. Results The study population consisted of 99 patients (62 female, 37 male) with a histologically confirmed diagnosis of AST, including age at presentation ranged from 2 to 70 years (mean 28.1 years, median 24 years). Of the 99 patients, 29 (29.3%) underwent sentinel lymph node biopsy, which showed evidence of micrometastases in three cases (10.3%); all three patients underwent complete lymph node dissection with no evidence of further metastasis. Considering the whole study population, the clinical outcome was excellent, as all of the patients have no evidence of recurrence or distant metastasis. The follow‐up period ranged from 6 to 216 months (mean 81.6 months, median 78 months). In addition, we collected data on the clinical and dermoscopic features of 26 lesions. The most frequent dermoscopic pattern observed was the multicomponent pattern (34.6%), followed by homogeneous (26.9%) and nonspecific (23.2%). In 66.7% of amelanotic ASTs, we observed glomerular (coiled) vessels uniformly distributed within the entire lesion, without asymmetry. Conclusion The results of our study with a long follow‐up show no recurrence or distant metastases, confirming the good clinical outcome, even in the case of sentinel lymph node positivity. From a diagnostic point of view, our series identified a typical dermoscopic picture for amelanotic ASTs, with a glomerular vascular pattern throughout the lesion in the absence of other dermoscopic parameters, making the correct diagnosis possible.

Cutaneous immune‐related adverse events (irAEs) occur in more than one‐third of patients treated with immune checkpoint inhibitors; they are often the first clinical manifestation, although they may occur months after initiation of therapy. We noticed that our patients usually have these cutaneous AEs on photodamaged skin. In fact, out of 19 patients being treated for metastatic melanoma, 8 (42%), all of whom had significant cutaneous actinic damage, developed cutaneous irAEs earlier and in a more serious form than those without such damage. Thus, we gave a high oral dose of nicotinamide (500 mg twice daily) to the patients with metastatic melanoma who had photodamaged skin, and continued this for the entire duration of the immunotherapy. The appearance of the first signs of cutaneous irAEs was 180 days after starting therapy in nicotinamide‐treated patients, compared with 65 days for patients not treated with nicotinamide.

Halo nevi, also known as Sutton nevi, are characterized by the development of a rim of depigmentation around a nevus. These nevi usually occur in healthy children or young adults as single lesions and are considered benign entities, whereas in adults, the sudden appear-