Pheochromocytoma Masked by Mutation in the TH Gene

[摘要] A 51-year-old woman consulting within the framework of investigation for abdominal discomfort, nausea, and vomiting underwent a computed tomography examination that revealed a well-delimited right adrenal heterogeneous mass measuring 8.2 × 8.3 cm with a native density of 40 Hounsfield units (HU)8. An 18F-deoxyglucose positron emission tomography scan showed a hypercaptation on the adrenal tumor of 7.4 SUVmax. Apart from these symptoms, the patient had no other complaint. Familial history was unremarkable. On examination, the patient was in good physical condition, arterial blood pressure was 136/85 mmHg, heart rate at 74 bpm.The measurement of plasma renin activity and aldosterone and the results of a 1-mg overnight dexamethasone suppression test ruled out primary hyperaldosteronism and Cushing syndrome. Catecholamine and metanephrine concentrations in multiple blood and urine samples were consistently within the reference interval and not compatible with the diagnosis of a pheochromocytoma (Table 1).View this table:Table 1. Concentrations of renin, aldosterone, cortisol, catecholamine, and their metabolites in urine and plasma found in the patient.aBecause the adrenal mass was not hormonally active, its surgical resection was performed without preoperative care. The removal of a mass weighing 356 g in the right adrenal gland was performed by open laparotomy.Histopathological analysis of tissue sections of the adrenal mass yielded an unexpected result: a pheochromocytoma was diagnosed on the basis of typical well-arranged nests called zellballen. This encapsulated adrenal tumor exhibits a low proliferation index (MIB-1, 1%–2%; 1 mitosis/high power field) without vascular invasion. Immunohistochemistry of the tumor sections revealed its neuroendocrine feature, with cells highly expressing CD56, chromogranin A, NSE, synaptophysin, and vimentin. Unfortunately, blood samples obtained before surgery were collected on heparin-coated tubes precluding serum chromogranin A assay. Because the unusual presentation of a “non–catecholamine-secreting pheochromocytoma” was in complete contradiction with the biochemical feature expected for these tumors, we …

[学科分类] 过敏症与临床免疫学