'Tiger woman sign' hypercalcaemia: a diagnostic challenge

Abstract

Hypercalcaemia is a common electrolyte abnormality with 90% of cases due to either primary hyperparathyroidism or malignancy. Other causes of hypercalcaemia often require careful consideration. We describe an approach to the assessment of hypercalcaemia, particularly where preliminary tests are inconclusive.This approach is illustrated by a case which posed a diagnostic challenge: a patient with significant hypercalcaemia due to acute atypical isolated sarcoid myositis. This case highlights an under-recognised clinical syndrome with distinct biochemical and radiological findings.

Keywords: PET; hypercalcaemia; sarcoidosis.

Fig 1.

A proposed approach to the initial investigation of hypercalcaemia. CT = computed tomography; FHH = familial hypocalciuric hypercalcaemia; CaSR = calcium sensing receptor; eGFR = estimated glomerular filtration rate; PTH = parathyroid hormone; TAP = thorax, abdomen and pelvis.

Fig 2.

Positron emission tomography showing diffuse fluorodeoxyglucose uptake isolated to muscles. This pattern of uptake is characteristic of sarcoid myositis and coined as ‘tiger man sign’.