54 yr M with a history of rectal cancer and type II diabetes presents to the emergency department with pain and erythema to the left buttock. Symptoms began last night with minimal irritation and he initially thought he had a rash. He awoke this morning with worsening pain, significant erythema and subjective swelling of the left buttock and associated subjective fevers. No N/V or diarrhea. No recent surgery or radiation therapy. No urinary symptoms. No other recent illnesses.
Vital signs were unremarkable. Physical exam revealed moderate erythema perianal tenderness and a large area of 8 x 8 cm of palpable induration. No areas of palpable fluctuance, visible drainage, skin lesions or visible evidence or trauma.
Suspecting an anorectal abscess, an IV was placed, labs sent and surgery was consulted. Given the patient’s history of rectal cancer, an IV contrast pelvic CT scan was obtained.
- What is the arrow indicating?
- What life-threatening diagnosis must be considered?
- What is the treatment?
- What is the prognosis?