Diagnosis of pheochromocytoma and paraganglioma. Focus on chromogranin A

Abstract

Objective. To analyze the results of a laboratory examination for chromogranin A in the blood performed in the laboratory at Almazov National Medical Research Centre in patients with confirmed diagnosis of pheochromocytoma/paraganglioma (PPGL) and in patients with unconfirmed neuroendocrine tumor based on the results of a comprehensive examination and to determine the possibilities of this method in the diagnosis of PPGL. Design and methods. A single-center retrospective cohort study was conducted. Electronic medical histories of patients with valid chromogranin A blood test in the period from 2015 to 2021 were studied. The patients included in the study were divided into 2 groups. Group 1 (study group) included 51 patients with a confirmed diagnosis of PPGL, and Group 2 (control group) included 120 patients, who were examined for suspected neuroendocrine tumor, but the diagnosis was not confirmed. The threshold value of chromogranin A was determined using ROC-analysis, the presence of PPGL was selected as a dependent variable. Results. The median of chromogranin A in the study group was 495,93 µg/l (0–100). According to the ROC-analysis, the optimal point of separation of the chromogranin A value for the diagnosis of PPGL with a test sensitivity of 82,4 %, specificity of 94,2 % (area under curve AUC — 0,939, standard error — 0,024, 95 % confidence interval — 0,892–0,986, p < 0,001) was 97,2 µg/l. After dividing patients with PPGL into 3 subgroups, depending on the size of the adrenal gland formation and the prevalence of the lesion according to computer tomography (less than 5 cm — subgroup 1, 5 cm or more — subgroup 2, multiple lesion — subgroup 3), the sensitivity of the threshold value of chromogranin A 97 µg/l in subgroup 1 was 70 %, in subgroup 2 — 95 % and in subgroup 3 — 82 %. Conclusions. Performing a blood test for chromogranin A can be used as an effective marker of PPGL, complementing the standard methods of laboratory diagnostics. This indicator may be an additional factor in the diagnosis of PPGL, especially in the presence of large formations, but the absence of an increase in chromogranin A should not be used to exclude the diagnosis.