Myeloid sarcoma of the skull base: a brief review of the literature and a rare case confused radiologically with end plaque meningioma.

[BACKGROUND] Myeloid sarcoma (MS) involving the skull base is an exceptionally rare clinical entity, with limited cases described in the literature. Due to its radiological similarity to meningiomas and other extraaxial lesions, MS often leads to misdiagnosis and delayed treatment. Insights from reported cases suggest that early histopathological confirmation and systemic therapy are critical for improving prognosis.

[OBJECTIVE] To present a rare case of skull base MS mimicking en plaque meningioma and to contextualize its clinical, radiological, and pathological features with respect to existing literature, emphasizing key diagnostic and therapeutic challenges.

[CASE AND LITERATURE CONTEXT] A 56-year-old man with a history of acute myeloid leukemia presented with a new-onset seizure. MRI showed a 38 × 37 mm extra-axial skull-base mass radiologically read as en plaque meningioma, with perilesional edema and suspected extension toward the right brachial plexus. Subtotal resection was performed for decompression and diagnosis. Histology revealed immature myeloid cells with CD43+, CD45+, CD33+, CD117+, CD68+, focal MPO+, CD34-; the Ki-67 index was 80-90%, indicating highly proliferative, aggressive biology. The postoperative course was uneventful without new deficits; mild headaches improved.

[CONCLUSION] This case underscores the diagnostic challenge of skull-base MS due to radiological mimicry and highlights an unusual brachial plexus extension, broadening its clinical spectrum. biopsy, prompt systemic therapy, and multidisciplinary management are essential, particularly in the presence of a very high Ki-67.