Both the macular and the infiltrative biopsy specimens showed the same pathologic features. Examination of hematoxylin-eosin–stained histologic sections demonstrated a spindle cell process involving dermis and subcutaneous tissue. The tumor was well circumscribed and composed of uniform, bland-appearing cells, some of which had a wavy nucleus. There was mucin between the spindle cells. There were no melanophages or increase in melanin or melanocytes either epidermally or dermally. The findings were characteristic of a neurofibroma.
Enlarging Congenital Pigmented Plaque—Diagnosis. Arch Dermatol. 2004;140(6):751. doi:10.1001/archderm.140.6.751-e