Impact of hypothyroidism on primary anal malignant melanoma: a rare entity.

Primary melanoma of the anal canal is rare and highly malignant condition, which is 1% of all invasive tumors in this site. This condition is often mistaken for benign conditions as either hemorrhoids or rectal polyp. Thyroid-stimulating hormone stimulation causes high proliferation of malignant melanoma. The association of hypothyroidism with primary malignant melanoma of anal canal is very rare. We are reporting such a very rare case.