Granulocytic sarcoma of the rectum: a rare complication of myelodysplasia

Area of Science:

• Oncology
• Hematology
• Gastroenterology

Background:

• Myelodysplastic syndromes (MDS) are a group of clonal hematopoietic stem cell disorders.
• Extramedullary manifestations of myeloid malignancies are uncommon but can present with diverse clinical features.
• Rectal bleeding and diarrhea are common gastrointestinal symptoms that can be associated with various pathologies.

Observation:

• A 67-year-old male with a history of myelodysplasia presented with a six-week history of rectal bleeding and diarrhea.
• Barium enema revealed an irregular polypoid filling defect in the proximal rectum near the rectosigmoid junction.
• Histological examination confirmed the presence of granulocytic sarcoma (extramedullary granulocytic leukemia; chloroma) infiltrating the rectal wall.

Findings:

• Granulocytic sarcoma, also known as chloroma or extramedullary granulocytic leukemia, can mimic other colorectal lesions.
• A low index of suspicion for this rare malignancy can lead to diagnostic delays and misdiagnosis.
• Immunohistochemical staining, specifically chloroacetate esterase, is essential for confirming the granulocytic origin of the tumor cells.

Implications:

• Increased awareness and a high index of suspicion are necessary for the early diagnosis of granulocytic sarcoma in patients with myelodysplastic syndromes.
• Accurate diagnosis through specialized stains like chloroacetate esterase is critical for appropriate treatment and management.
• This case highlights the importance of considering rare extramedullary presentations of myeloid malignancies in the differential diagnosis of colorectal symptoms.