Poorly differentiated colon carcinoma with neuroendocrine features presenting with hypercalcemia and cutaneous metastases: case report and review of the literature.

Humoral hypercalcemia is rarely associated with colon carcinoma; cutaneous metastases from colon carcinoma are also infrequent. To the authors' knowledge, no cases of colon carcinoma presenting with both hypercalcemia and cutaneous metastases have been reported to date. A case of advanced poorly differentiated colon carcinoma with neuroendocrine features with both humoral hypercalcemia of malignancy (HHM) and cutaneous metastases is presented. A poorly differentiated colon carcinoma with neuroendocrine features occurred in a 42-year-old patient with metastases to the liver, both femurs, left orbit, and scalp. The hypercalcemia was caused by the expression of a parathyroid hormone related peptide by both the primary and cutaneous metastatic tumors. Bisphosphonate treatment helped normalize serum calcium in a few days, but hypercalcemia recurred approximately 3 weeks later. Chemotherapy only mildly reduced the size of the cutaneous metastases. The patient died 8 months after initial diagnosis. To the authors' knowledge, the case presented in the current study is the first to be reported with both HHM and cutaneous metastases. Hypercalcemia and cutaneous metastases are separately associated with a poor prognosis and indicate advanced and widely metastatic disease. Although still unclear, the mechanism by which colon cancer causes cutaneous metastases and hypercalcemia, in light of current theories presented in the literature, is discussed.