Myelolipoma in the spleen: a rare discovery of extra-adrenal hematopoietic tissue
We report a case of a 64-year-old Caucasian man with a past medical history of gout, dyslipidemia, hypertension, obesity, gastroesophageal reflux disease and in previous left hemicolectomy for colon cancer nine years prior to presentation. His past surgical history includes two laparoscopic hernia repairs for incisional hernias after the hemicolectomy. He was referred to the surgery service for new diagnosis of myasthenia gravis and the consideration for possible thymectomy. The thymus was without evidence of thymoma, however, the work-up included radiographic studies demonstrating a centrally located splenic mass measuring 8 × 6.8 cm. The density of the mass was consistent with those found in soft tissue tumors (Fig. ). A comparison CT study from 9 years previous demonstrated a smaller mass (4.7 cm) in the same anatomic location with similar density levels. There had been no prior treatments. The patient's case was presented at our multi-specialty tumor board and elective resection of the spleen was recommended due to the possibility of malignancy.\nExploratory laparoscopy was performed revealing significant adhesions necessitating conversion to laparotomy. An uncomplicated splenectomy was performed. Before surgery the patient was vaccinated against (Streptococcus pneumonia, Haemophilus influenza and Neisseria meningitides). Grossly, a 380-g spleen measuring 15 × 13 × 7 cm with intact splenic capsule was removed. Serial sections reveal a yellow-tan to red-tan, well-circumscribed tumor mass, measuring 10 × 10 × 7 cm. The tumor was grossly surrounded by a thin rim of dark red splenic parenchyma with splenic capsule. All sections showed a well-circumscribed area of myelolipoma completely contained within the splenic capsule (Fig. ). The tumor consisted mainly of adipose tissue with multifocal areas of non-dysplastic hematopoietic tissue (confirmed with immunohistochemical assay positive for glycophorin and Factor VIII demonstrating erythroid elements and megakaryocyte presence). Containment within the splenic capsule was microscopically confirmed. These findings confirmed the diagnosis of intrasplenic non-neoplastic myelolipoma.