Background: Chromogranin A (CgA) belongs to the family of granins, proteins which are an integral part of the secretory granules of neuroendocrine cells in endocrine glands and the diffuse neuroendocrine system. While it has become standard clinical practice to measure serum CgA in neuroendocrine tumors, various other non-endocrine conditions may increase this markers concentration and lead to diagnostic problems.
Case report: We present the case of a 57-year-old female patient who was diagnosed with acromegaly based on the typical clinical, hormonal, and imagistic criteria in 2007. She underwent surgery, radiation therapy, and medical therapy with a somatostatin analog until the disease was finally controlled in 2012. She also presented with an important co-morbidity rheumatoid arthritis. During an annual follow-up for acromegaly, she presented with skin flushing, and purplish-red skin lesions on the neck and cheeks, which raised the suspicion of carcinoid syndrome. This was disproved by normal serotonin and 5-HIAA levels, but the patients CgA level was, by contrast, twice the normal. This prompted us to screen for MEN 1 syndrome, but the diagnosis was refuted by normal calcium, iPTH, and prolactin levels, and a normal abdominal CT scan. We looked for other common causes of high CgA, but the patient had no history of proton pump inhibitor therapy, gastric disorders, or heart disease, and her kidney function was normal. Of great importance was the dermatologic evaluation, which concluded that the patients skin lesions were highly suggestive of cutaneous lupus erythemathosus. Since her underlying rheumatic condition was severe, with a DAS-28-ESR score of 5.8, and generalized manifestations of the disease, including pulmonary fibrosis, rheumatoid nodules, and secondary osteoporosis, the patient was referred to a rheumatology clinic for further investigations and treatment.
Conclusions: Although CgA is a useful tool in the evaluation of neuroendocrine tumors, there are several other causes of potentially false positive results, the majority of which are related to proton pump inhibitor therapy, impaired renal function, and autoimmune gastritis. Rheumatic diseases, such as rheumatoid arthritis and lupus erythemathosus, are rarer causes of elevated CgA. The reason for this, while still partially unknown, is presumed to be the generalized inflammation, suggested by the correlation between CgA and tumor necrosis factor-α levels. It was also observed that CgA levels are unusually elevated in patients with generalized manifestations of rheumatoid diseases, which was also the situation of our patient.
18 May 2019 - 21 May 2019