Approximately 1% of all malignant tumours and 3% of malignant tumours of the skin are malignant melanomas.11
Albinism is an autosomal recessive disorder of melanin synthesis that affect the skin, eyes and hair. Melanocytes are normally distributed in the eye and skin, but normal amounts of melanin are not synthesised.12
The most frequently encountered tumour is squamous cell carcinoma, with basal cell carcinoma seen less often.12 13
Malignant melanoma is very rare in oculocutaneous albinism,12 14
but this low incidence is unexplained.12
The present case was a albino woman with malignant melanoma of nevoid type. The term nevoid malignant melanoma is used to describe rare nodular malignant melanoma that may escape detection in routine histological sections due to lack of a prominent intraepidermal component, slight pleomorphism and evidence of partial maturation with descent into the dermis. Nevoid melanoma mimics ordinary compound or intradermal melanocytic nevi. Furthermore, melanomatous skin cancer presents a greater diagnostic challenge in albino patients because of their hypopigmented appearance. In our patient because of the rarity of association of oculocutaneous albinism with malignant melanoma, especially the nevoid type, further investigation in addition to histopathological examination under light microscopy was carried out. Immunohistochemistry analysis for S100 and HMB-45 demonstrated the melanocytic nature of the neoplasm.
- Melanocytic tumours are rare in albino patients and their diagnosis is difficult.
- Nevoid melanoma is an uncommon subtype of malignant melanoma and because of its deceptive morphological features is usually misdiagnosed as melanocytic nevus.
- Some studies have shown a better than expected prognosis for nevoid melanoma, but this has not been confirmed and sufficient follow-up is needed.
- We believe the association of nevoid melanoma with oculocutaneous albinism in this case merited attention.