A case report on 111In chloride bone marrow scintigraphy in management of adrenal myelolipoma.

Adrenal myelolipoma is a benign hormone-inactive tumor composed of hematopoietic tissue and mature adipose tissue. Because this tumor tends to be rich in fat, in many cases it can be diagnosed based on computed tomography (CT) or magnetic resonance imaging (MRI) findings alone. However, in the presence of much necrosis, calcification and hematopoietic tissue and/or the absence of much fat, and in cases with tumor apoplexy, this tumor becomes difficult to differentiate from other tumors. In such cases, a bone marrow scan may be informative as a non-invasive imaging diagnostic method for preoperative diagnosis of the tumor and determination of the method for the surgical treatment. We herein report a case of huge adrenal myelolipoma with the non-adipose portion identified using an Indium chloride (InCl3) bone marrow scan. A 69-year-old woman was referred to our hospital because of a left peritoneal mass detected on a medical checkup. Abdominal CT revealed a mass measuring 14.3 cm in diameter located between the left kidney and the left adrenal gland, which showed coexistence of fat and soft tissue densities. A bone marrow scan is a nuclear medicine examination to assess hematopoietic activity. To avoid excessive resection of the tumor, we thought that a bone marrow scan could be applied for differentiation between myelolipoma and retroperitoneal liposarcoma by evaluating the hematopoietic activity of the tumor. Tumor enucleation was performed, and pathological examination showed a diagnosis of adrenal myelolipoma. The patient was treated with laparoscopic enucleation. No metastatic recurrence was found during 8 months of follow-up. Diagnosis of myelolipoma by CT and MRI becomes difficult in the presence of a high volume of hematopoietic tissue. In such cases, a bone marrow scan may be informative as a non-invasive imaging diagnostic method for preoperative diagnosis of the tumor and determination of the method of surgical treatment.