MRI findings are consistent with infected branchial cleft cyst with intramuscular abscesses of the left sternocleidomastoid muscle.

Pathology:

Aspiration of 20 cc of creamy fluid with cytological examination of the films and cell block prepared from the aspirate reveals keratinized squamous cells, polymorphonuclear leukocytes, macrophages, inflammatory cells and red blood cells. Cytology concludes secondary infected branchial cyst.