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Year : 2019  |  Volume : 62  |  Issue : 1  |  Page : 165-166
Gingival choristoma masquerading as fibroma

1 Department of Oral Pathology and Microbiology, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India
2 Department of Oral and Maxillofacial Surgery, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India

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Date of Web Publication31-Jan-2019

How to cite this article:
Laxmidevi B L, Marimallappa T R, Mahadesh J. Gingival choristoma masquerading as fibroma. Indian J Pathol Microbiol 2019;62:165-6

How to cite this URL:
Laxmidevi B L, Marimallappa T R, Mahadesh J. Gingival choristoma masquerading as fibroma. Indian J Pathol Microbiol [serial online] 2019 [cited 2019 Jul 24];62:165-6. Available from: http://www.ijpmonline.org/text.asp?2019/62/1/165/251239

The term osseous choristoma (OC) was first introduced by Krolls et al. acknowledging the tumor-like growths of microscopically normal tissue in an unusual location.[1] However, OC has been called by many terminologies in the literature, and it needs to be differentiated from other soft tissue and bone tumors.[2] The origin of such OCs is debatable suggesting both developmental and or traumatic etiology.[1] OC is seldom reported in gingiva.[2] Here, we report one such case.

An 18-year-old male patient reported to our institution for a growth in the upper anterior region for 2 months. His family and medical history was nonsignificant. Intraorally a well-defined, solitary, oval-shaped mass was seen between the maxillary central incisors, measuring 2 × 1 × 1 cm, pedunculated, pale pink in color, nontender, firm in consistency, and was attached to the marginal gingiva [Figure 1]. The radiograph was not contributory, and the lesion was excised under local anesthesia without much effort using a surgical blade with minimal bleeding. The tissue was sent for histopathological examination with a provisional diagnosis of fibroma.
Figure 1: Intraoral photograph showing the mass on the anterior maxilla

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Microscopically, the lesion revealed stratified squamous parakertinized epithelium with underlying connective tissue showing well-circumscribed trabeculae of normal viable bone with entrapped viable osteocytes in the lacunae and few osteoblasts lining the bony surface [Figure 2]. The trabeculae showed marrow spaces containing fibro-fatty tissue with adipocytes, collagen fibers, and blood vessels. Compaction of collagen fibers was seen surrounding the whole lesion, suggesting OC of gingiva. The lesion healed uneventfully.
Figure 2: Trabeculae of normal viable bone with entrapped viable osteocytes in the lacunae and osteoblasts lining the bony surface (H and E, ×100)

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Monserrat was the first to report an osseous lesion in the tongue in 1913 and labeled it as “lingual choristoma.” Krolls et al. in 1971 changed the term to “osseous choristoma,” defining it as a mass consisting of normal cells in an abnormal location. He used the term choristoma instead of osteoma as he noticed that these lesions were not osteogenic in origin and did not progressively enlarge like benign lesions.[1] OC by definition is a normal bone tissue in an abnormal location, which can be in the skin (previously known as osteoma cutis) or in the oral mucosa (previously known as osteoma mucosae).[2] According to Gnepp, these extraskeletal osteomas which occur in the buccal mucosa, tongue, and nasal cavity are not true neoplasms and should be termed as choristomas.[3] Frequently observed choristomas of the oral cavity consist of bone, cartilage, or both, and these have been called soft tissue osteomas or soft tissue chondromas; however, Neville reported that choristoma was a better term because they do not appear as a true neoplasm.[4]

There are various discussions regarding the etiopathogenesis of OCs. Proliferation of the bone or cartilage in oral and maxillofacial soft tissues probably reflects the embryonic rest cells as origin. It is also thought that pluripotential stem cells which can differentiate to osteocytes and chondrocytes results in ectopic formation of bone and cartilage. However, some of these proliferations seem to occur as a result of local trauma or chronic inflammation leading to metaplastic ossification.[2],[5] In our case, the patient revealed a history of trauma, supporting a posttraumatic theory of origin.

Differential diagnosis of OC can be considered depending on the location. Clinically, gingival masses will embrace many differential diagnoses such as fibroma, peripheral ossifying fibroma (POF), peripheral giant cell granuloma, pyogenic granuloma, peripheral odontogenic tumors, etc.[2] However, those with histological features showing close resemblance to OC include, POF, exostosis (tori), and peripheral osteoma. Differentiating from POF is not much difficult as it shows unique cellular stroma of oval and primitive mesenchymal cells and is found exclusively on alveolar bone surfaces; in contrast bone marrow is not produced by POF, thus lacking the bone like organization seen in OC.[2],[5]

Possibility of solitary torus can be eliminated as they arise from the bone with borders merging with it and usually seen below the attached gingival mucosa.[2]

It is necessary to differentiate OC from peripheral osteoma which shows exactly similar histopathological features that are sometimes difficult to distinguish. These peripheral osteomas (also called periosteal, paraosteal, or exophytic depending on origin) are true osteogenic neoplasms arising from the periosteum of bone or alveolar process. On radiographs they appear as oval, radiopaque, well-circumscribed mass attached by a broad base or pedicle to the host bone cortex. OCs do not show any such relation to the underlying bone and peripheral osteomas continue to grow unlike OCs, which cease to grow after attaining a certain size.[6]

We did not consider heterotopic ossification which on histology shows plump fibroblasts and reactive bone with osteoblastic rimming as they are exclusively present in the muscle.[5] Our lesion does not seem to arise from the periosteum of the maxillary alveolar bone. Neither the radiograph nor the histopathology showed any relation with the underlying bone. Considering all aforementioned features and differential diagnosis, we arrived at the diagnosis of OC of gingiva.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Bastian TS, Selvamani M, Ashwin S, Rahul VK, Cyriac MB. Osseous choristoma of the labial mucosa: A rare case report. J Pharm Bioallied Sci 2015;7:S725-7.  Back to cited text no. 1
Rajendran R, Sivapathasundaram B. Benign and malignant tumors of oral cavity. In: Rajendran R, Sivapathasundaram B, editors. Shafer's Text book of oral pathology. 7th ed. India: Elsevier a division of Reed Elsevier India Private Limited; 2012. p. 81-222.  Back to cited text no. 2
Gnepp DR. Bone lesions. In: Gnepp DR, editor. Diagnostic surgical pathology of the Head and Neck. 2nd ed. Philadelphia: Saunders Elsevier; 2009.p.729-84.  Back to cited text no. 3
Neville BW, Damn DD, Allen CM, Bouquot JE. Soft tissue tumors. In: Neville BW, Damn DD, Allen CM, Bouquot JE, editors. Oral and Maxillofacial Pathology. 3rd ed. India: Elsever; 2009. p. 507-70.  Back to cited text no. 4
Venugopal R, Bavle RM, Mallar KB, Rakesh P. Osteocartilaginous choristoma of buccal mucosa: A rare entity. J Oral Maxillofac Pathol 2014;18:478-80.  Back to cited text no. 5
[PUBMED]  [Full text]  
Johann AC, de Freitas JB, de Aguiar MC, de Araújo NS, Mesquita RA. Peripheral osteoma of the mandible: Case report and review of the literature. J Craniomaxillofac Surg 2005;33:276-81.  Back to cited text no. 6

Correspondence Address:
B L Laxmidevi
Department of Oral Pathology and Microbiology, Sri Siddhartha Dental College and Hospital, Tumkur - 572 107, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_204_18

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