What anatomical structure is indicated by a soft tissue mass on the floor of the mouth?

A soft tissue mass on the floor of the mouth is most commonly indicative of the opening of Wharton's duct. Wharton's duct is the major excretory duct of the submandibular gland, which drains saliva into the oral cavity. When there is a blockage, inflammation, or a stone in the duct, it can lead to swelling and the formation of a soft tissue mass in that area.

While the sublingual gland is located nearby, the duct's opening is a more precise identifier for a localized soft tissue mass specifically. Gingival tissue primarily relates to the gums, and any mass in the floor of the mouth would not typically be attributed to this tissue. The lingual frenulum is a fold of tissue that connects the underside of the tongue to the floor of the mouth and is not usually associated with soft tissue masses that present as a distinct swelling. Therefore, the opening of Wharton's duct is the most accurate anatomical structure associated with this presentation.