How do you explain the fistula?

This patient was referred to me after being looked at by his periodontist and restorative dentist. They were confused and so was I by the initial presentation.

Patient: 62 year-old male with atrial fibrillation managed with Digoxin

Chief Complaint: ”Bump on gums”

Dental History: The patient presented with a history of a noticeable lesion at the marginal labial gingival between the maxillary right lateral incisor (#7) and canine (#6). It was first noticed 3 weeks before the consultation visit with the author. Both a periodontist and general dentist had examined the tooth and referred the patient for a third opinion. Level 2/10 pain was described as being intermittent.

Significant Findings: The referring restorative dentist provided a radiograph showing a fistula tracing to the cervical interproximal area most near the canine root surface. Clinical examination revealed slight bleeding upon probing at the mid-labial area with normal circumferential probing depths. There was slight sensitivity upon percussion with Class 1 mobility. Cold thermal testing was within normal limits and the electric pulp test yielded a normal response as it did with all neighboring teeth.

Radiographic and CBCT findings suggested a lingual anomaly on #7.

What is the diagnosis, prognosis and treatment plan?