A 27-year-old female patient presented with a history of swelling in mandibular left posterior region for 1 year and pain for 1 month [Figure 1]. Intraoral examination revealed a bony hard swelling extending from the left mandibular second premolar till retromolar area. Obliteration of buccal and lingual vestibule was noted. The mucosa overlying the lesion appeared normal. The patient had undergone extraction of mandibular first molar of the same side earlier.
The radiographic examination revealed a multilocular radiolucency involving left mandibular region [Figure 2a and b]. The lesion extended from the second premolar and posteriorly it involved the coronoid and the condylar processes. The expansion of buccal and lingual plate of the mandible was evident on occlusal radiographic images. Differential diagnoses of ameloblastoma and keratocystic odontogenic tumor were considered. Incisional biopsy confirmed the diagnosis of follicular ameloblastoma. Based on the histopathological diagnosis, segmental block resection was carried out with the surgical margin 1 cm away from the radiographic boundary of the lesion. The excised specimen was sent for histopathological diagnosis. No evidence of recurrence was noted after 1 year of resection.
The gross specimen showed expansion of buccal and lingual plates of mandible and bone erosion in the retromolar area. On grossing, a large cystic lesion was noted involving body and ramus of mandible. Microscopic examination of the excised tissue specimen revealed follicles of ameloblastoma of varying sizes [Figure 3a]. The stroma was mature, collagenous and it demonstrated foreign body granulomas with numerous multinucleated giant cells [Figure 3b and c]. On careful examination, it was evident that these foreign body granulomas were associated with multiple, amorphous, eosinophilic masses enclosed in densely hyalinized eosinophilic matrix/rings [Figure 3b and c].
Histochemical staining was done to understand the nature of hyaline rings. The hyaline rings were periodic acid-Schiff positive [Figure 3d]. The peripheral portion of the foreign body was positive for Masson's trichrome stain suggesting it to be condensation of collagen.
To prove the similarity of the foreign body and plant cells, grains such as gram, wheat, rice, split pigeon pea were boiled and processed. Moreover, vegetables such as carrot, cabbage were processed raw. The sections were stained with hematoxylin and eosin and periodic acid-Schiff. We observed that a section of a legume [Figure 4b] bore a striking resemblance, to the foreign body we encountered. Both the legume and the foreign body showed peripherally smaller angular to rectangular cells and centrally larger cells enclosing amorphous substance. When viewed under polarized light, the hyaline structures exhibited birefringence [Figure 5a and b] and the fragments of material similar to hyaline rings were noted within the giant cells [Figure 5c and d].
Based on these observations, the foreign bodies were identified as remnants of food particles of vegetable origin. To rule out other local and systemic granulomatosis, hematological investigations were done, and the results were within normal limits. Tuberculosis was ruled out by normal findings of chest radiography and negative tuberculin test. Hence, the lesion was diagnosed as follicular ameloblastoma with PG. Patient's consent has been obtained for publishing clinical findings and images.