Sacral extramedullary haematopoiesis, radiologically mimicking malignancy

Area of Science:

• Hematology
• Radiology
• Oncology

Background:

• Extramedullary haematopoiesis (EMH) is the formation of blood cells outside the bone marrow, typically in the liver, spleen, and lymph nodes.
• EMH presenting as a destructive sacral lesion with a presacral soft tissue mass is rare and can be mistaken for malignancy.
• Accurate diagnosis is critical, especially in pregnant patients with suspected hemolytic anemia.

Purpose of the Study:

• To highlight a rare case of extramedullary haematopoiesis mimicking sacral malignancy.
• To emphasize the importance of considering EMH in the differential diagnosis of sacral lytic lesions with presacral masses.
• To underscore the utility of MRI and biopsy in diagnosing atypical EMH and excluding malignancy.

Main Methods:

• Case presentation of a pregnant woman with suspected hemolytic anemia.
• Initial imaging workup revealing a destructive sacral lesion and presacral mass.
• Advanced MRI evaluation to assess the nature of the presacral mass and subsequent biopsy for definitive diagnosis.

Main Results:

• Imaging initially suggested primary sacral malignancy with metastases.
• MRI revealed the presacral mass had signal characteristics consistent with hematopoietic tissue, suggesting EMH.
• Definitive diagnosis of EMH was confirmed, differentiating it from malignancy.

Conclusions:

• Extramedullary haematopoiesis should be considered in the differential diagnosis of sacral lytic lesions with presacral masses, alongside common malignancies.
• Magnetic Resonance Imaging (MRI) plays a key role in characterizing presacral masses and suggesting EMH.
• Biopsy remains essential for confirming atypical EMH and definitively excluding malignant etiologies.