Endocrine Abstracts

Introduction

Extramedullary hematopoiesis (EMH) refers to hematopoiesis occurring outside the bone marrow. Pathologic EMH can be caused by thalassemias or disorders in the hematopoietic system. Sites of EMH can be widespread however, most common localizations are in the spleen, liver, and lymph node

Case report

A 22-year-old male patient was referred to the endocrinology department for bilateral adrenal masses found on computed tomography (CT). The patient had been followed up at the hematology department for thalassemia major with 2 units of erythrocyte suspension replacement per month, occasionally less frequently because of patient’s incompatibility. Splenectomy was done at the age of 6. Abdominal CT revealed a 50 × 35 mm mass in the right adrenal gland and 45 × 33 mm mass in the left adrenal gland. The patient had no symptoms and signs compatible with functioning adrenal adenoma such as involuntary weight gain, hypertension, etc. There was no anorexia, weight loss, smoking history associated with malignancy. The patient’s height was 161 cm, weight was 68 kg, and BMI was 26.2 kg/m². Blood pressure was 125/75 mmHg and pulse was 65 beats/min and rhythmic. Leucocyte: 11 900, Hb:10.7 g/dl, Htc: 34%, PLT: 76 7000, Ferritin: 700 ng/ml. Adrenal functioning tests revealed no functioning. Abdominal MRI showed a 34 × 46 mm, well-circumscribed, solid mass in the right adrenal gland and 33 × 44 mm solid mass in the left adrenal gland, in out-of-phase sections without significant signal loss. The signaling feature might be compatible with an low-fat-content adenoma or non-adenomatous mass. Positron emission tomography (PET) with fluorodeoxyglucose (18F-FDG) done for malignancy exclusion showed mild FDG uptake in both adrenal masses (SUVmax for the left and right adrenal masses 2.3 and 2.4, respectively) with no other pathological uptake. Bilateral adrenal masses were thought to be due to EMH. Fluorothymidine (18F-FLT) PET imaging was performed. FLT-PET demonstrated peripheral nonhomogeneus increased FLT uptake in both adrenal glands with SUVmax 8.2 in the left adrenal gland and SUVmax 6.7 in the right adrenal gland. EMH was confirmed by adrenal biopsy from the periphery of the left adrenal gland where intense FLT uptake was observed.

Conclusion

Bilateral adrenal masses due to EMH are very rare in the literature. 18F-fluoro-3-deoxy-L-thymidine (18F-FLT) is a DNA precursor and its uptake is related to the proportion of DNA synthesis in hematopoietic cells. 18F-FLT PET/CT offers a unique and non-invasive method for three dimensional localization and quantification of functional bone marrow. It can be used to differentiate masses that could be due to EMH in atypical locations.