To describe the characteristics of five pediatric patients with the Meyerson phenomenon associated with congenital melanocytic nevi, five cases were reviewed to retrieve information relating to clinical presentation, treatment and evolution of the eczematous phenomenon and of the nevi. Three of five patients were male. Mean age at presentation of the Meyerson phenomenon was 23 months (range: 4 mos-4 yrs). Three patients presented with only one halo eczematous lesion, while two patients presented with more then one halo eczematous lesions. The halo eczematous lesions were located on the leg, arm, and trunk in four, two, and two patients, respectively. All were associated with congenital melanocytic nevi with overlying hypertrichosis. Four were treated with topical corticosteroids, and five developed some degree of hypopigmentation within the nevic lesion. In children with Meyerson phenomenon associated with congenital hairy melanocytic nevi, neither trigger to the eczematous eruption nor preferential gender or anatomical site location was identified. The Meyerson phenomenon evolved towards hypopigmentation of the congenital melanocytic nevic lesions in all patients but no other cutaneous changes were observed on follow-up.

Plexiform fibrohistiocytic tumor is a very rare fibrohistiocytic tumor of intermediate malignancy. It can occur at any age but is more prevalent in children and in young adults. Here we present the clinicopathologic findings of three girls with this tumor. The patients were 8 months, 14 months, and 7 years of age. They each presented with a solitary, nontender, subcutaneous nodule or plaque. Light microscopy and immunohistochemical study findings were compatible with plexiform fibrohistiocytic tumor. We also review the previously published cases in the English-language literature.