A 29-year-old African American male presented to our emergency department with a 5-day history of perineal pain and tender swelling of the left perineal body with no evidence of trauma. Physical examination revealed a firm left proximal corpus cavernosum body. Laboratory tests were within normal limits. Pelvic MRI confirmed the presence of a large left-sided unilateral corporal cavernosum partial thrombosis filling the proximal third of the left corpus cavernosum. The patient was managed conservatively with anticoagulation, pain control, and pelvic rest. At 3-month follow-up, perineal imaging showed reduction of thrombus size and resolution of pain and swelling. At 6-month follow-up, a penile ultrasound demonstrated almost complete resolution of the thrombus.