Pediatric acute leukemia presenting as bilateral renal enlargement. Report of a case with fine needle aspiration cytologic features suggestive of megakaryocytic differentiation.

BACKGROUND

Fine needle aspiration (FNA) cytologic diagnosis of acute myeloid leukemia involving the kidney has rarely been reported, but acute leukemia with cytologic features suggestive of megakaryocytic differentiation has not been described before.

CASE

An 8-month-old male presented with an abdominal swelling, bilateral cervical and inguinal lymphadenopathy and enlarged left epididymis. Ultrasonography of the abdomen revealed a space-occupying lesion in the liver and bilateral enlargement of the kidneys. FNA smears from the right kidney and right submandibular lymph node showed numerous blast cells. Since rare blast cells were positive for myeloperoxidase, a cytodiagnosis of involvement by acute myeloid leukemia (AML) was made. However, following the hematologic diagnosis of acute megakaryoblastic leukemia (M7) from peripheral blood and bone marrow smear examination, FNA smears were reviewed. There were cytoplasmic blebs or protrusions in the blast cells and cytologic features suggestive of their differentiation toward micro-megakaryocytes and megakaryocytes. There was also evidence of shedding of platelets, including numerous giant platelets. The reviewed FNA cytodiagnosis was suggestive of AML (M7).

CONCLUSION

Extramedullary involvement by acute megakaryoblastic leukemia (M7) can be suspected based on cytomorphologic features in FNA smears.