Key Clinical Message:
Here we report on a challenging diagnosis of a VIAHS patient who presented with atypical clinical features of perianal abscess with fistula formation, fever, aphthous ulcers, bicytopenia, and hematochezia at a very early age of disease onset. This case highlights the consideration of ADA2 deficiency as a differential diagnosis of enlarging cutaneous abscess with no evidence of wound healing in the setting of leukopenia and neutropenia.