Unusual case of hyperpigmentation
Heba El-Gayar & Owais Chaudhri
Cutaneous pigmentation results from the synthesis of melanin by the melanocytes. Its distribution pattern in the surrounding keratinocytes determines the actual colour of the skin. ACTH and α-MSH are equipotent at the melanocortin-1 receptor (MC-1R) that is expressed on the cell surface of melanocytes. Activation of these receptors stimulates both proliferation of melanocytes and melanin synthesis.
We present the case of a 66-year-old lady. Originally from Ghana, she has lived in the UK for over 40 years. She presented with an 18 months history of generalised hyperpigmentation. Cortisol day curve and a random ACTH were both normal. A skin biopsy showed a normal number of melanocytes but with hyperpigmentation of the dermis and epidermis. Levels of α-MSH levels were undetectable in the plasma. MRI pituitary was normal. Imaging revealed an octreotide avid lesion within the mid zone of the left lung. Unfortunately CT thorax following the octreotide scan did not show any corresponding lesion.
Her skin continued to darken. She went back to Ghana for a holiday where unfortunately she was shunned by her family, as there was a belief that she was cursed. She is extremely desperate for a cure however but is not keen on having surgery.
Discussion: Our α-MSH assay is validated for in vitro release from hypothalamic explants. Its accuracy on plasma samples is unknown. An α-MSH secreting tumour therefore cannot be excluded. Other options for therapy include octreotide or surgery. However, the success of therapy will be difficult to judge as any improvement in this ladys skin colour is likely to be slow.