A Diagnostic Pitfall in Lumbar Radiculopathy: Isolated Lumbar Myeloid Sarcoma Initially Interpreted as Disc Herniation

Myeloid sarcoma (MS) is a rare extramedullary malignant tumor composed of immature myeloid precursor cells, most commonly associated with hematologic disorders, such as acute myeloid leukemia, but occasionally presenting as an isolated lesion without bone marrow involvement. We report the case of a 59-year-old woman who presented with right-sided radicular pain and sensory deficit in the L4 dermatome. Initial non-contrast lumbar magnetic resonance imaging (MRI) revealed a lesion posterior to the L4 vertebral body that was interpreted as a superiorly migrated disc herniation, leading to medical management with symptomatic improvement. One month later, the patient returned with rapidly progressive lower extremity weakness. Contrast-enhanced MRI demonstrated a diffusely hypointense lesion on T1- and T2-weighted images with marked homogeneous enhancement and epidural extension. Emergency decompressive laminectomy and tumor debulking were performed. Histopathological examination showed atypical myeloid cells that were positive for MPO, CD33, and CD43, confirming the diagnosis of MS. The patient subsequently received adjuvant chemotherapy and radiotherapy following multidisciplinary evaluation. This case highlights the diagnostic challenges of isolated MS, particularly when radiological findings mimic common degenerative spinal conditions. Although spinal involvement is uncommon, and lumbar localization is even rarer, MS should be considered in the differential diagnosis of atypical spinal lesions, especially in patients with unexpected clinical progression. Early use of contrast-enhanced MRI and prompt histopathologic evaluation are essential for accurate diagnosis. Surgical decompression may be required in the presence of neurological deterioration, while combined chemoradiotherapy remains the recommended approach for systemic disease control. Awareness of this rare entity is crucial to avoid diagnostic delays and to facilitate timely, appropriate management.

Myeloid sarcoma disc herniation lumbar spine