Chloroma

Chloroma, also called granulocytic sarcoma or myeloid sarcoma, is an extramedullary tumor composed of immature myeloid cells (myeloblasts) that accumulate outside the bone marrow. The name chloroma derives from a greenish hue observed in some lesions due to the enzyme myeloperoxidase, though color can be variable.

Chloroma most often occurs in association with acute myeloid leukemia (AML) or other myeloid neoplasms such as myelodysplastic syndromes, and less commonly with myeloproliferative neoplasms. It can present concurrently with systemic leukemia, at relapse, or, in some cases, as an isolated tumor before leukemia is diagnosed.

Lesions have been described in skin, soft tissues, lymph nodes, orbit, bone, periosteum, the gastrointestinal tract, and the central nervous system. Clinical presentation depends on location and may include a palpable mass, swelling, pain, neurologic deficits, or visual impairment.

Definitive diagnosis relies on histopathology with immunohistochemistry showing myeloid markers, most commonly myeloperoxidase positivity. It must be distinguished from lymphomas and other tumors; ancillary tests and clinical context aid in diagnosis. Imaging with CT, MRI, or PET assists in staging and treatment planning.

Management typically involves systemic chemotherapy tailored to AML, as extramedullary disease usually reflects, or predicts, systemic disease. Local treatment with radiotherapy or surgical resection may be used for symptom control or mass reduction. Prognosis is linked to the underlying leukemia; isolated chloroma without detectable leukemia carries a substantial risk of progression to AML over months to years.