Sialo-cutaneous fistula with ectopic submandibular gland sialolith, revealing a hidden ipsilateral enlarged and elongated styloid process: a consideration based on CT findings.

Sialolithiasis is a common salivary pathology, and an uncommon complication of sialadenitis and sialolithiasis is the formation of fistulous tracts to other compartments. Submandibular gland sialo-oral fistulae are not particularly remarkable, given the location of the gland and Wharton's duct, but submandibular sialolith-associated fistulae to other cervico-facial compartments (transcervical sialo-cutaneous and sialo-pharyngeal fistulae) are much less common. We report herein an unusual case of a 49-year-old obese man with sialo-cutaneous fistula containing a large, ectopic sialolith in subcutaneous tissue that was expected to undergo spontaneous elimination, but revealed hidden Eagle syndrome featuring an ipsilateral enlarged, elongated styloid process. Furthermore, we offer a thorough review of the literature regarding sialo-fistulae and highlight the relationship between an abnormal styloid process and submandibular sialadenitis with sialolithiasis and new tract formation based on computed tomography.