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.

This study was designed to use nested polymerase chain reaction (nested PCR), in situ hybridization (ISH) and immunohistochemical techniques to identify human papillomavirus (HPV) in tissues fixed in formalin and embedded in paraffin. Eighty cases including 17 cases of condyloma acuminatum, 10 cases of cervical dysplasia, 6 cases of carcinoma in situ, 16 cases of squamous cell carcinoma of the uterine cervix, 14 cases of nasal and paranasal papilloma, 1 case of transitional cell papilloma and 16 cases of esophageal squamous cell carcinoma were examined. With the nested PCR method, the positive reaction rate of HPV was higher than with the single step PCR method. The detection rate was about ten-fold higher in condyloma acuminatum and two times higher in cervical dysplasia with the nested PCR method. In four cases of condyloma acuminatum, ISH was positive. Three of those cases were type 18 HPV and the another was type 11 HPV. Immunohistochemically, HPV was detected only in the cases of condyloma acuminatum. The nuclei of superficial epithelial cells, especially kilocytes reacted positively both by ISH and immunohistochemical methods. Nested PCR is not a very complicated technique, and the detection rate is higher than that of commonly used pathological techniques. These results suggest that nested PCR will be a useful test for HPV routine pathological diagnosis.

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