A trout fisherman with hypercalcaemia and skin lesions

A 67-year-old trout fisherman presented with a six-week history of polyuria, polydipsia, dyspnoea on exertion and the development of subcutaneous extensor surface skin nodules. He was hypercalcaemic with acute renal impairment. Parathyroid hormone was suppressed and vitamin D levels were within normal limits. The patient had a past history of hypothyroidism, but thyroid replacement was adequate. Hypoadrenalism, myeloma and metastatic malignancy were excluded. Biopsy of a subcutaneous nodule revealed dermally based non-caseating granulomata, consistent with sarcoidosis. Serum angiotensin-converting enzyme was elevated, and computerized tomography scanning of the chest and abdomen revealed widespread lymphadenopathy with multiple lung nodules and splenomegaly. Prednisolone therapy produced rapid resolution of his skin lesions and normalization of his bone and renal biochemistry. The mechanism of hypercalcaemia in sarcoidosis is poorly understood but is thought to involve parathyroid hormone-independent 1-hydroxylation of 25-hydroxyvitamin D within sarcoid lesions. This process may be exacerbated by exposure to UV light and it is of interest that this patient developed symptoms after a period of intense trout fishing in the good weather of April and May 2007.