Giant pigmented tumour of the scalp—a diffuse neurofibroma or a congenital naevus showing neurofibromatous changes? Immunohistochemical and electron microscopic studies

Abstract

A case of giant pigmented tumour of the scalp which developed in a 47-year-old woman is reported. Macroscopically, the tumour showed a peculiar two-layered structure, consisting of an upper non-pigmented and a lower pigmented portion. Histologically, it was composed of elongated neurofibromatous tumour cells with abundant collagen fibres in the non-pigmented portion and round naevus-like cells with abundant melanin pigment in the pigmented portion. S-100 protein and neurone-specific enolase were demonstrated in most of the tumour cells, but neurofilament and myelin basic protein were not detected. Electron microscopy revealed melanosomes in the tumour cells of the pigmented portion. These findings might support a melanocytic origin for the tumour, but the lack of superficial pigmentation and the associated hair loss were against this. The tumour may represent an example of duality of neural crest differentiation.

A Case of Diffuse Neurofibroma of the Scalp

“…Meissner bodies are characteristic, but are not always present. Neurofibromatous tissues show immunoreactivity with S-100 protein, a sensitive, but non-specific, marker of benign nerve sheath tumors 9 .…”

Giant cerebriform naevus of the scalp

“…Lever and Schaumburg-Lever described variably extensive GCN lesions [15] that often expressed both a neural-like arrangement [12] and a discrete tendency to malignant transformation [5,8,9,16]. Our experience did not record any transformation; however clinical and radiological examinations should be performed in order to exclude any CNS malformation; only histology supports the differential diagnosis of organoid naevus, nevrilemmona and some pilaf tumors of the scalp which all look very similar to GCN [13].…”

Hemifacial mass with extensive intralesional ossification and fat

“…Wagner-Meissner bodies may be seen and the tumour cells show diffuse staining with antibodies against S-100 protein. 10 Surgical excision is the mainstay in the treatment of diffuse neurofibromas. The aim of surgery is to restore cosmesis and address occasional symptoms associated with the size of the tumour.…”