THE UTILITY OF SULFUR COLLOID SCANS IN EXTRAMEDULLARY HAEMATOPOIESIS: AN UNUSUAL CASE REPORT.

Abstract

Introduction: Extramedullary haematopoiesis (EMH) refers to the production of cellular blood components outside the bone marrow. It often involves the liver and spleen and paravertebral regions. Documented cases of EMH on sulfur colloid scans are rare. Aim(s): To report on the utility of a sulfur colloid scan in the diagnosis of EMH in an unusual location. Method(s): Retrospective review of sulfur colloid scans, and calcium phytate colloid scans, between 2004 and 2024 at a large Victorian tertiary public health system. Report on a rare case of pre-sacral EMH in a complex patient with warm autoimmune haemolytic anaemia (wAIHA). Results and Discussion: Retrospective review of 119 sulfur colloid and calcium phytate scans performed at our institution between 2004 and 2024 found that 89.92% of cases queried characterisation of liver lesion/s, 6.67% queried EMH and 3.33% queried asplenia or splenic infarct. This report presents a case of 99mTc-Sulfur Colloid scan where EMH was identified in an uncommon location, the pre-sacral region. The patient is a 72-year-old female being managed for a myriad of haematological disorders including wAIHA, a rare and life-threatening condition with complex treatment regimens. Surveillance MRI of two enlarging lobulated pre-sacral masses thought to be nerve sheath tumours or paragangliomas raised the potential need for surgical excision/biopsy. Multi-disciplinary review of the MRIs noted the presence of fat in the lesions, triggering the new differential diagnosis of extra-adrenal myelolipoma or EMH. A 99mTc-Sulfur Colloid scan was performed and demonstrated mild avidity in the pre-sacral lesions, similar to bone marrow uptake, confirming the clinical suspicion of EMH therefore negating the need for risky surgical intervention. Conclusion(s): EMH is an uncommon indication for sulfur colloid scans and is seldom found in the pre-sacral region. The usual treatment for EMH with hydroxycarbamide risks suppression of reticulocytosis that could worsen the anaemia in this patient. Findings of the sulfur colloid scan were pivotal in the diagnosis of EMH in the pre-sacral lesions and significantly impacted ongoing treatment planning in this diagnostically challenging case.