Anatomic mapping and clinicopathologic analysis of benign acral melanocytic neoplasms: A comparison between adults and children.

BACKGROUND: The clinicopathologic features of benign acral melanocytic neoplasms (BAMNs) remain poorly understood.

OBJECTIVE: To define the clinicopathologic features of BAMNs.

METHODS: We analyzed clinical data and mapped BAMNs anatomically. We also reviewed the histopathologic features of BAMNs and compared these between adults and children.

RESULTS: We included 396 cases of BAMN: 335 adults and 61 children (376 acquired and 20 congenital lesions). Anatomic mapping revealed that the nonweight-bearing portion of the foot was the most common site in adults (120/335, 35.8%) and the forefoot the most common site in children (17/61, 27.9%) for BAMNs. The long axes of the BAMNs paralleled the dermatoglyphic lines on the palms and soles, as did most tissue sections. The lesion diameters were <5.7 mm in all acquired lesions. Histopathologically, we diagnosed 69 lentigo simplex, 201 junctional, 114 compound, 8 intradermal, and 4 blue nevi. Corneal pigmentation, nests located between rete ridges, dendrite prominence, and cytologic atypia were all significantly more common in children than adults.

LIMITATIONS: The retrospective study design and acquiring patients from a single institution of a single country limited the research results.

CONCLUSION: BAMNs develop most commonly on nonweight-bearing regions of the soles in adults and on the forefoot in children. The long axis of the lesion follows the dermatoglyphics, and cytologic atypia is more common in children.