KAT6A::EP300 fusion in congenital myeloid sarcoma: Yet another novel molecular marker indicating spontaneous remission?: A case report.

RATIONALE: Acute myeloid leukemia (AML)/myeloid sarcoma (MS) is risk-stratified based on cytogenetics. Although most congenital AML/MS have a dismal prognosis, certain genetic variants such as t (8, 16) [KAT6A::cAMP response element-binding protein (CREB) - binding protein fusion] and more recently t (8, 22) [KAT6A::EP300 fusion] have shown spontaneous remissions. KAT6A located on chromosome 8p11 encodes KAT6A protein, a histone/lysine acetyltransferase enzyme. Numerous partner genes associated with KAT6A include cAMP response element-binding protein (CREB) - binding protein (16p13), EP300 (22q13), LEUTX (9q13), NCOA2, NCOA3, and ASXL2.

PATIENT CONCERNS: In this article, we describe an otherwise healthy infant who presented with skin nodules on the face and scalp without any systemic or CNS involvement. A biopsy of the cutaneous lesion was consistent with congenital MS.

DIAGNOSES: Through molecular testing, we found that our patient had the KAT6A::EP300 mutation. This is one of the rare recurrent cytogenetic abnormalities that are linked to congenital AML.

INTERVENTION: Our patient underwent spontaneous remission with watchful waiting.

OUTCOME: Our patient has remained in spontaneous remission for 24 months.

LESSONS: Even though the KAT6A::EP300 mutation in adults is a poor prognostic marker, a similar mutation in congenital AML has a higher likelihood of spontaneous remission. Hence, conservative management might be an initial management strategy for clinically stable patients.