Answer to last month's Clinical Quiz

Question:
A 56 years old man complained of mild itchiness over the pigmented lesion on his back in the past 3 months. He claimed that the papule was present for more than two years without symptoms until recently and that it had grown very slowly. He noticed some bleeding after scratching the lesion. There was no family or personal history of skin cancers.

Answer:
C. Irritated seborrhoeic keratosis

Seborrhoeic keratoses are very common lesions that are found in middle aged and elderly. They often appear as sharply delineated, round or oval, brown to very black warty plaques with a shiny greasy surface. Sometimes they may show an inflammatory halo as in this case. They usually present as a stud, papule or plaque on the skin surface with no infiltration or underlying induration. The sudden onset of numerous seborrhoeic keratoses is called Leser-Trelat sign which has been reported to be associated with internal malignancy, namely adenocarcinoma of stomach, lymphoma, leukaemia, bronchial or breast tumours. The differential includes pigmented basal cell carcinoma and malignant melanoma. Pigmented basal cell carcinoma frequently commences with a small translucent pearly papule. Later, the border of the basal cell carcinoma still retains this feature with fine telangiectatic vessels. Central ulceration and rolled border are characteristics of nodular basal cell carcinoma. Superficial spreading malignant melanoma is rare in this locality and it should progress more rapidly and with some irregularity of border. Common wart will not be pigmented though the end on view of the capillaries may appear as dark dots. In suspicious cases, skin biopsy can easily differentiate this benign entity.