Clinicopathologic and Dermoscopic Features of 20 Cases of Spark's Nevus, a Dermoscopic Simulator of Melanoma

Spark's nevus is a particular type of melanocytic nevus, with histology that shows features of both Spitz and Clark nevus. Detailed dermoscopic features in a series of Spark nevi have not been described yet. We performed a monocentric retrospective observational study on 20 lesions of Spark nevus excised from 19 patients (M:F = 10:9; mean age: 37,6 years), reviewed by 5 experts in dermoscopy and 2 dermatopathologists. A histologic review confirmed that Spark nevi were mostly symmetric (80%), well circumscribed (100%), mainly compound (65%) melanocytic lesions with either epithelioid (55%) or spitzoid (45%) cell morphology and bridging of the nests (100%). Spark nevi were more frequently found on the trunk (85%) in patients with a history of sunburns in childhood (84%), with skin phototype III (79%), and with high nevus count (>100 nevi, 7 patients (36%)). On dermoscopy, we observed different general patterns: multicomponent (40%), reticular-globular-homogeneous (15%), globular homogeneous (15%), reticular (15%), reticular-globular (5%), homogeneous (5%), and globular (5%). Spark nevi showed frequently dermoscopic asymmetry (63%), brown color (90%) with areas of central hyperpigmentation (41%) and peripheral hypopigmentation (28%), atypical pigment network (48%), irregular globules (42%), irregular dots (31%), irregular blotches (16%), blue-whitish veil (13%), peripheral island (25%), irregular hyperpigmented areas (12%), and regression (33%). BRAF mutation was present in 7 of the 10 analyzed cases (70%); all these cases presented a history of evolution. In conclusion, Spark nevi occur on the trunk of young adults with high nevus count and history of sunburns; dermoscopic features are protean, often atypical and suspicious of melanoma.

Automated summary

Spark's nevus is a unique type of melanocytic nevus, exhibiting characteristics of both Spitz and Clark nevus. The histologic and dermoscopic features of Spark nevi were analyzed in a retrospective study of 20 excised lesions. The nevi showed symmetrical and well-circumscribed features, with predominantly compound cell morphology and presence of bridging of the nests. Dermoscopically, various patterns and features were observed, including asymmetry, brown color, atypical pigment network, irregular globules, and areas of hyperpigmentation and hypopigmentation. BRAF mutation was common in cases with a history of evolution. Spark nevi are frequently atypical and suspicious of melanoma.