BACKGROUND
Spontaneous abscesses are generally typical in patients with significant risk factors and have been linked to numerous muscle groups. The sternocleidomastoid muscle, however, piqued our interest as an unusual location, especially in this patient who, other than diabetes mellitus, had no associated risk factors or signs of trauma.
CASE REPORT
A 61-year-old man appeared with neck pain, erythema, and swelling that had been present for 9 days and for which he had previously been examined in the Emergency Department. He was discharged on oral doxycycline after initial computed tomography (CT) of the neck revealed infiltration without collection. He returned with worsening symptoms and new-onset fever and chills. Vital signs were normal on assessment, with no evidence of trauma. Swelling was observed near the right sternocleidomastoid muscle insertion. A repeat CT scan of the neck revealed an abscess 2.5 cm in diameter. He was originally treated with empiric antibiotics before being moved to targeted medications. Incision and drainage were completed without complication. The patient was given a 6-week course of oral antibiotics.
CONCLUSIONS
Spontaneous intramuscular abscesses are uncommon in people who have had no previous trauma or other known risk factors, but could be encountered in diabetic patients with non-optimal blood glucose levels, due to bacteremia. As a result, these cases require a high level of suspicion to be recognized and treated early. The scarcity of literature on this illness makes determining the cause challenging. However, by highlighting this case, we intend to raise awareness and facilitate early diagnosis and treatment.

Keywords: Abscess; Neck Muscles; Neck Pain; Pyomyositis; Subcutaneous Tissue