Teaching NeuroImages: Sacral spine chloroma

A 23-year-old man with recurrent acute myeloid leukemia (AML) underwent successful reinduction and was judged posttherapy to be in complete remission. Soon thereafter, he complained of pain in his left buttock radiating into his left posterior thigh. Neurologic examination was unremarkable. Radiographic evaluation demonstrated a left S2 lesion suggestive of a nerve sheath tumor (figure 1). An open biopsy was performed that revealed a chloroma pathologically (figure 2), sometimes referred to as a myeloid sarcoma.^1,2 Most chloromas are found in patients with recurrent AML and are overwhelmingly intracranial.¹ Infrequently, chloromas are paraspinal, and in this location present with epidural spinal cord compression.² Intraspinal invasion by a chloroma is rare. Systemic evaluation confirmed recurrent AML, for which he was successfully treated with reinduction and whole-body irradiation followed by an allogeneic transplant. He is currently disease-free and neurologically asymptomatic 1 year posttransplant.

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Figure 1 Intra-axial and extra-axial sacral chloroma

Coronal (A) and axial CT (C) images show left S2 nerve root enlargement (black arrowheads) with adjacent osseous erosion of the left S2 foramen (black arrow, C). Gadolinium-enhanced T1-weighted MRI with fat suppression shows corresponding sacral nerve root enhancement (white arrows) on coronal (B) and axial (D) images, consistent with sacral nerve chloroma.

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Figure 2 Medium- and high-power (inset) photomicrographs of a hematoxylin & eosin–stained section of the sacral lesion

Note the high nuclear: cytoplasmic ratio, irregular nuclei, frequent apoptosis, and scattered mitotic figures. Scale bars: medium power 0.4 mm; high power 20 μm.

• © 2013 American Academy of Neurology