A 2 cm Buccal Mucosa Mass, Tooth 309, and What Pyogenic Granuloma Actually Is
Vetopathy · Case Spotlight · Feline
A 13-year-old neutered male domestic shorthair was presented for difficulty chewing on the left side of the mouth. Oral exam revealed a roughly 2 cm, nodular mass on the buccal mucosa adjacent to the left mandibular first molar (309) — a location that lined up exactly with the left-sided chewing avoidance reported at home.
Why this looked concerning
A nodular oral mass of this size in a geriatric cat still starts the workup in the same place: ruling out squamous cell carcinoma, which remains the leading concern for any feline oral mass regardless of exactly where in the mouth it sits. The buccal mucosa location also puts eosinophilic granuloma complex on the differential list — feline "indolent ulcers" and eosinophilic granulomas favor the lip margins and buccal mucosa, and can look grossly similar to a reactive mass at this site. Neither differential can be settled by appearance or location alone; both require histopathology to sort out from a straightforward reactive process.
What the biopsy showed
The specimen showed abundant granulation tissue subjacent to an overlying ulcerated epithelium, admixed with abundant mixed inflammatory cells. There was no neoplastic epithelial population and no infiltrative growth pattern consistent with squamous cell carcinoma. The histologic pattern was also not the collagen degeneration with palisading granulomatous inflammation that characterizes eosinophilic granuloma complex — this was a reactive vascular and fibrous tissue proliferation, not a collagenolytic one. The final diagnosis was a pyogenic granuloma: exuberant, ulcerated granulation tissue arising as a reactive process, essentially the same underlying entity as the more commonly described sublingual chewing lesion, occurring here at the buccal mucosa instead.
Why the distinction matters
The location tells the mechanical story here. A mass on the buccal mucosa directly adjacent to a mandibular molar is positioned exactly where it would be caught and traumatized by the opposing dentition on every bite — which is a reasonable explanation both for why the lesion kept regenerating as friable, ulcerated granulation tissue, and for why this cat was specifically avoiding chewing on that side. Once a lesion like this is large enough to be reliably struck by the opposing teeth, it tends to perpetuate itself: trauma produces granulation tissue, granulation tissue is fragile and ulcerates easily, and the cycle continues until the mechanical irritation is removed along with the mass.
As with the sublingual form, the management implication is significant. A pyogenic granuloma is treated with local excision and carries an excellent prognosis. Squamous cell carcinoma at the same site would mean a substantially more guarded conversation — wider margins, possible staging, a different prognosis entirely. A 2 cm ulcerated buccal mass in a 13-year-old cat is exactly the kind of finding that could reasonably be over-treated on gross appearance alone; histopathology is what confirmed this was the reactive process rather than the malignant one.
Eric Snook, DVM, PhD, DACVP — Vetopathy. Have a case where the gross appearance and the histopathology told two different stories? I'd love to feature it here — reach out any time.