A case of raised CA 19–9 in a patient with desmoplastic fibroblastoma of the upper limb

Carbohydrate antigen 19–9 (CA 19–9) is a tumor marker widely accepted as the most useful blood test in diagnosing and monitoring pancreatic cancer. However, CA 19–9 may also be raised in other conditions such as colorectal, hepatic, lung, and ovarian carcinoma as well as benign conditions such as hepatobiliary and pulmonary diseases. CA 19–9 is rarely elevated above 200 U/ml in benign conditions with values exceeding 1000 U/ml being highly suggestive of malignancy. The mechanism of secretion in both malignant and benign conditions remains unclear. Desmoplastic fibroblastoma (DF) is a benign soft tissue tumor. CA 19–9 has not been reported in association with DF previously. We present a case of raised serum CA 19–9 in a 71-year-old male attributed solely to DF in his left cubital fossa. The patient’s CA 19–9 level rose from 56 U/ml at the time of presentation to 3763.8 U/ml over a period of 9 months. Post-DF excision, the CA 19–9 level decreased to 1464 U/ml at 1 month, 162.3 U/ml at 2.5 months, and 24U/ml, within normal range, at 7 months post-surgery. CA 19–9 levels continued to remain at 24 U/ml 1.5 years post-tumor excision. The CA 19–9 level in this patient was highly elevated which is unusual in association with a benign tumor. The rate of decrease in CA 19–9 level post-excision was in keeping with that reported after pancreatic cancer resections. This is the first case of DF in association with raised CA 19–9.