2023 年 70 巻 1 号 p. 43-46
Adrenal incidentaloma is a clinically unapparent adrenal mass more than one cm in diameter detected during imaging performed not for adrenal disease. A 34-year-old man was evaluated for AI with a diameter of 3.5 cm in the left adrenal. He was obese with body mass index of 33,9. Blood pressure was 110–120/90 mmHg. The general laboratory tests were unremarkable. An adrenal hormone screening set revealed that ACTH was 6.9 pg/mL, cortisol 14.9 μg/dL, renin activity 0.9 ng/mL/h, aldosterone 79.4 pg/mL, dehydroepiandrosterone-sulfate (DHEA-S) measured on two occasions 5,217 ng/mL and 6,477 ng/mL (gender- and age-adjusted reference values, 1,060–4,640 ng/mL). The levels of metanephrine and normetanephrine were normal. The tumor was thought to produce solely DHEA-S. The excised left adrenal tissue contained a tumor with a diameter of 26 mm and neighboring adrenal tissue. The tumor consisted mostly of acidophil cells without necrosis, capsular or vascular invasion, and mitosis. Immunohistochemical study revealed followings: the cells of the tumors were stained positive for 3β-hydroxysteroid dehydrogenase, and 17α-hydroxylase, and 11β-hydroxylase, weakly positive for DHEA sulphotransferase, and negative for aldosterone synthetase. The atrophy of neighboring tissue was presumably caused by excess cortisol production. Four months after surgery, the cortisol level was 11.2 μg/dL and DHEA-S level 1,462 ng/mL. The tumor is considered to be a cortisol-producing adenoma with modestly excessive DHEA-S production rather than isolated DHEA-S-producing adenoma. Immunohistochemical study of steroidogenic enzymes is a valuable addition to blood hormone measurement to clarify steroid production profile.
IN RECENT YEARS, adrenal tumor is occasionally found because of frequent utilization of image studies of a variety of disorders. Adrenal incidentaloma (AI) is defined as a clinically unapparent adrenal mass greater than 1 cm in diameter detected during imaging performed for reasons other than for suspected adrenal disease [1]. Patients with AI have to be screened for excess hormone production unless image studies suggest malignancy. Guidelines of two endocrinology societies recommend measurements of cortisol and aldosterone in addition to careful evaluation of symptoms and signs of excess hormones [2, 3]. As most patients with incidentally discovered tumors do not have clinical manifestations of hormone excess, they do not want complicated tests. Therefore, hormone screening is preferably done by one single blood sampling. Since 2021, we use a hormone screening set, in which ACTH, dehydroepiandrosterone-sulfate (DHEA-S), renin activity, aldosterone, metanephrine, and normetanephrine are measured. Measurement of DHEA-S is included for following reasons: low serum levels of DHEA-S have been reported in patients with subclinical Cushing syndrome (SCS) [4-7], low DHEA-S levels are proposed to be employed for prediction [8] and screening [9] of SCS, and consequently only patients with low DHEA-S levels are to be further studied by overnight dexamethasone suppression test.
We encountered an AI patient with DHEA-S levels elevated above age- and gender-adjusted reference levels. Laparoscopic left adrenalectomy was done for presumed isolated DHEA-S-producing tumor. The excised tissue was studied with immunohistochemical staining of steroid synthesizing enzymes to investigate the steroid production profile of the tumor.
A 34-year-old man was evaluated for a round mass with a diameter of 3.5 cm in the left adrenal which had been incidentally found in a chest abdomen computed tomography (CT) scan, which itself had been done for the blunted cost-phrenic angle on the right side found in the chest radiogram. The patient had been treated for hypertension with amlodipin before the CT scan for three years. His height was 175 cm, weight 104 kg, and body mass index 33.9. The blood pressure under hypertension treatment was 110/90 mmHg in the right arm and 120/90 in the left. The hemoglobin was 15.9 g/dL, hematocrit 47.8%, white blood cell count 5,100/μL with normal differential counts. Fasting glucose level was 111 mg/dL, creatinine 0.83 mg/dL (eGFR 88.6 mL/min/m2), sodium 143 mmo/L, potassium 3.6 mmol/L, and chloride 106 mmol/L. The total protein was 7.1 g/dL, albumin 4.7 g/dL. Alkaline phosphatase was 119 u/L, γ-GPT 170 u/L, AST 93 u/L, and ALT 133 u/L. The results of the adrenal hormones screening set were as follows: ACTH was 6.9 pg/mL, cortisol 14.9 μg/dL, renin activity 0.9 ng/mL/h, aldosterone 79.4 pg/mL, DHEA-S 5,217 ng/mL on one occasion and 6,477 ng/mL on another occasion (gender- and age-adjusted reference value, 1,060–4,640 ng/mL), metanephrine 30.3 pg/mL (reference range, <130 pg/mL), and normetanephrine 68.9 pg/mL (reference range, <506 pg/mL). The ratio of aldosterone concentration to renin activity was 88.2. The echography of the abdomen revealed enlarged liver with dull edge and increased liver/kidney contrast, indicative of fatty liver.
Weight reduction and caloric restriction had been advised and the hypertension had been treated amlodipine. As the tumor was thought to produce excess DHEA-S, left adrenalectomy was planned because of a possible association of excess DHEA-S and hypertension [10]. The patient underwent laparoscopic left adrenalectomy. Post-operatively he showed no clinical manifestations suggestive of adrenal insufficiency. Four months after surgery, the blood pressure remained modestly elevated, i.e., 140 mmHg systolic and 100 mmHg diastolic and weight reduced by only 3 kg. The cortisol level was 11.2 μg/dL, ACTH level 46.1 pg/mL, and DHEA-S level 1,462 ng/mL.
Macroscopically, the excised left adrenal tissue contained an encapsulated tumor with dark brown surface measuring 26 × 26 × 23 mm. The tumor adjoined the non-tumorous tissue. The cells in the tumor, consisting of acidophil cells and pale cells with the former dominant (Fig. 1A), appeared similar to cells of the normal adrenal cortex, which proliferated in nest and in cord. Necrosis, capsular or vascular invasion, and mitosis were not observed. Concerning cell cycle-associated proteins, p16 and p21 were positive in small numbers of cells and Ki-67 labeling index was positive in ca. 2% of cells. The tumor was diagnosed as adrenal cortical adenoma.
Histology of the adrenal tumor and immunohistochemical studies of the tumor and the adjacent adrenal tissue
(A) Hematoxylin eosin staining. (B)–(E) Immunohistochemical studies of the tumor using antibodies to (B) 3β-hydroxysteroid dehydrogenase (3βHSD), (C) 17α-hydroxylase (P450C17), (D) DHEA sulphotransferase (DHEA-ST), (E) 11β-hydroxylase (CYP11β1), and (F) aldosterone synthetase (CYP11β2); magnification 170×. (G) and (H) Immunohistochemical studies of the adjacent adrenal tissue, loupe magnification.
The immunohistochemical staining of the tumor cells was positive for 3β-hydroxysteroid dehydrogenase (3βHSD), 17α-hydroxylase (P450C17), 11β-hydroxylase (CYP11B1) (Fig. 1B–D), weakly positive for DHEA-sulfatransferase (DHEA-ST) (Fig. 1E) and negative for aldosterone synthetase (CYP11B2) (Fig. 1F). The methods of Immunochemical stain of each enzyme were published elsewhere [11] and that of CYP11B2 was in another article [12]. In the adrenal cortex adjacent to the tumor (Fig. 1G), 3βHSD-positive cells were present in the zona reticularis and the part presumed to be the zona fasciculata was narrower. CYP11B2-positive cells were scarcely present in the cortex neighboring the tumor (Fig. 1H). From these findings, it appears that the steroidogenesis in the neighboring cortex had been suppressed by excess production of cortisol by the adenoma.
As obesity and hypertension persisted four months after the surgery, both conditions appear unrelated to AI. DHEA-S level was elevated above age- and gender-adjusted reference range before surgery and the level reduced 4 months after surgery, which was consistent with DHEA-S production by the tumor. Adrenal carcinoma accounts for 6% of tumors that are 4.1 to 6 cm and 25% of tumors that are greater than 6 cm in diameter [13]. Tumor size and DHEA-S level are positively related to malignancy [14]. The CT scan for AI showed no irregularity of the contour, calcification, nor necrosis in the central area. Before the surgery, we felt sure the tumor was producing DHEA-S in excess. We did not seriously consider SCS because of SCS reportedly associated with reduced DHEA-S levels [4-9]. Nonetheless, SCS could not be denied in this patient because of elevated levels of DHEA-S. Adrenal cortical tumors have been studied by immunohistochemical staining of enzymes involved in steroid biosynthesis [6, 15]. Immunohistochemical study of the tumor was performed to examine whether the tumor was malignant and solely producer of DHEA-S. Malignancy was denied by histological findings and analysis of cell cycle-associated proteins. The immunohistochemical study showed positive staining of the enzymes involved in cortisol biosynthesis, i.e., 3βHSD, P450C17, and CYP11B1. In the neighboring atrophic adrenal cortex, 3βHSD content in the zona reticularis was considerably reduced and CYP11B2-positive cell were absent, which was consistent with suppressed steroidogenesis in the neighboring cortex conceivably by excess cortisol production. In spite of modestly elevated DHEA-S levels, isolated DHEA-S production is unlikely because of weakly positive DHEA-ST stain. The tumor of the present patient is concluded to be a cortisol-producing adenoma with modestly excessive production of DHEA-S. In retrospect, we might have better perform a dexamethasone suppression test while waiting for the planned surgery.
DHEA-S is one of the adrenal androgens and secreted from the adrenal cortex as sulfated product of dehydroepiandrosterone (DHEA). AI with excess production of DHEA-S is rare. A multi- center survey of AI in Italy revealed DHEA-S levels were decreased in 12 of 24 patients and normal in the rest [16]. The authors found only one non-cancer AI patient with excess DHEA-S production in the literature, i.e., a 57-year-old woman presented with generalized scalp thinning without acne and excessive body hair as a manifestation of excess androgen [17]. Clinical manifestations of modestly excessive androgen in man are imperceptible. If DHEA-S had not been included in the hormone screening set, the tumor might have persisted without adrenalectomy. Measurement of DHEA-S levels will hopefully be included in hormone screening set for AI. Post-operative histochemical study of steroidogenic enzymes will be very helpful to define endocrine diagnosis.
The authors declare that they have no conflict of interest.
Informed written consent was provided by the patient.
