Final Diagnosis -- Myeloid Sarcoma in CNS, Subdural Hematoma and Meningothelial Meningioma

FINAL DIAGNOSIS

The final diagnoses were:

1. myeloid sarcoma in CNS, as a blast transformation of chronic myelomonocytic leukemia (CMML),
2. subdural hematoma
3. meningothelial meningioma (WHO Grade I).

DISCUSSION

We found a rare and challenging case of a CMML associated brain myeloid sarcoma coexisting with meningothelial meningioma and a subdural hematoma. CMML is a hematopoietic stem cell neoplasia, 16% of these patients undergo blast transformation (2) such an acute myeloid leukemia (AML) or rarely as a myeloid sarcoma (MS). MS is an extra-medullar tumoral mass constituted by a myeloid blast. There is a predilection for the fifth and sixth decades of life, with a median age of 55.8 years (range 16-87 years of age). MS can represent a blast transformation from AML, chronic myeloid leukemia (CML), myelodysplastic syndrome or CMML. MS may also develop de novo, isolated or concurrently with a myeloid neoplasia. Myeloid sarcoma in CMML patients has been reported to involve the testis, lymph nodes, and small intestine, but not the central nervous system (4). Nevertheless, pathologists have reported brain MS in patients with others myeloid neoplasms such as AML or CML. The diagnosis of brain MS is very challenging, especially without a known history of a myeloid neoplasm. Pathological studies show that MS is a proliferation of immature cells, including myeloblasts, monoblasts, promonocytes, or less commonly promyelocytes. Necrosis, numerous mitotic figures, and tingible-body macrophages are regularly present. The use of only hematoxylin-eosin stain can lead to misdiagnosis because MS can be confused in adults with diffuse large B-cell, plasmablastic or T cell lymphomas, melanoma, or poorly differentiated carcinoma. In children, the differential includes lymphoblastic, Burkitt's lymphomas or nonhematopoietic tumors-neuroblastoma, rhabdomyosarcoma, Ewing/primitive neuroectodermal tumor, or medulloblastoma (1, 3). For this reason, it is mandatory the use of immunochemistry. CD68 is the most commonly expressed marker followed by myeloperoxidase (MPO), CD117, CD99, lysozyme, CD34, TdT, and CD56. Intracranial hemorrhage is a known complication in patients with hematologic tumors associated with thrombocytopenia. Gadolinium enhancement on MRI could guide diagnosis -a marked uniform enhancement may be atypical in subdural hematoma. Although imaging changes in MS may mimic meningioma.

As highlighted in this case, brain findings in patients with CMML should raise the possibility of brain myeloid sarcoma. Our patient had circulating blast and AMC of 10x109/L, a risk factor for blast transformation in CMML (3). Meningioma has been reported to coexist with subdural hematomas, pituitary adenoma, neurofibromas, and vascular malformations. This case highlights the previously unrecognized possibility of CMML associated myeloid sarcoma involvement of the brain. Additionally, it also illustrates the complex diagnostic dilemma of coexisting pathologies in CMML patients. A high index of suspicious along with a detailed pathologic examination allows making an appropriate diagnosis.

REFERENCES

1. Klco JM, Welch JS, Nguyen TT, Hurley MY, Kreisel FH, Hassan A, Lind AC, Frater JL (2011) State of the art in myeloid sarcoma. Int J Lab Hematol 3(6):555-65.
2. Patnaik MM, Itzykson R, Lasho TL, Kosmider O, Finke CM, Hanson CA, Knudson RA, Ketterling RP, Tefferi A, Solary E (2014) ASXL1 and SETBP1 mutations and their prognostic contribution in chronic myelomonocytic leukemia: a two-center study of 466 patients. Leukemia 28(11):2206-12.
3. Patnaik MM, Wassie EA, Lasho TL, Hanson CA, Ketterling R, Tefferi A (2015 Blast transformation in chronic myelomonocytic leukemia: Risk factors, genetic features, survival, and treatment outcome. Am J Hematol 90(5):411-6.
4. Wilson CS, Medeiros LJ (2015) Extramedullary Manifestations of Myeloid Neoplasms. Am J Clin Pathol 144(2):219-39.

Contributed by Martha Romero, Carlos Saavedra, Myriam Rodríguez, Andrés F. Henao-Martínez