Cloacogenic anal carcinoma presenting with humoral hypercalcemia: report of a case

We present herein the case of a 60-year-old man found to have a rare type of cloacogenic anal carcinoma. The disease was advanced and aggressive with local invasion to the prostate as well as distant lymph node metastases to the neck and paraaortic region on presentation. Therefore, a palliative abdominoperineal resection was performed, 10 weeks following which the patient developed humoral hypercalcemia. Despite treatment with hydration, furosemide, steroids, and calcitonin, serum calcium continued to rise and the patient died on the 95th postoperative day. Laboratory findings revealed a decreased parathyroid hormone (PTH) level and marked elevation of parathyroid hormone-related protein (PTHRP). The detection of the PTHRP in the tumor extract and the positive immunohistochemical staining for this in the tumor cells suggested that the humoral hypercalcemia was definitely caused by its associated tumor production. Although hypercalcemia is not an uncommon complication of solid cancers in their late stage, only three other cases of rectal cancer with hypercalcemia have ever been reported. To our knowledge, this is the first documentation of cloacogenic anal carcinoma accompanied by PTHRP-induced severe humoral hypercalcemia.