†These authors contributed equally to this work.
2. Dr. med., Clinic for nuclear medicine, Kantonsspital Graubünden, Chur, Switzerland.
3. Dr. med., Clinic for endocrinology, Kantonsspital Graubünden, Chur, Switzerland.
Incidental hypercalcemia is a common clinical problem with a broad differential diagnosis. Primary hyperparathyroidism and cancer are the two most common aetiologies. In addition to existing clinical symptoms, the assessment of duration and degree of hypercalcemia, as well as measuring of parathyroid hormone are crucial to distinguish between them. Usually the diagnosis is not difficult to make. However, on the basis of our patient with localised invasive triple-negative lobular breast cancer and concomitant primary hyperparathyroidism we demonstrate that the reality can be different. Despite the best and most modern technologies, both diseases can be difficult to diagnose. Accurate diagnostics are always important, but even more relevant for the correct staging and subsequent therapies in life-threatening tumours. An association between breast cancer and primary hyperparathyroidism is well known and has been described in many case reports. However, in the cases documented in the literature, the two illnesses occurred sequentially and not at the same time. Here, we highlight the diagnostic and therapeutic challenges of the simultaneous occurrence of the two diseases localised breast cancer and primary hyperparathyroidism, when hypercalcemia is the first clinical finding.
Keywords: Triple-negative invasive lobular breast cancer, primary hyperparathyroidism, hypercalcemia, osteoprotection