| Abstrakt: |
An 18-year-old black male presented to the oral surgery resident clinic for evaluation of a radiolucent lesion of the right posterior mandible detected on routine panoramic imaging at a local pediatric dental clinic. The patient was otherwise healthy with no significant past medical or social history. The patient's mother vaguely recalled that "something" was seen several years ago on a radiograph of the area, but a search of dental records found no images for comparison. On extraoral exam, the patient appeared symmetric without evidence of facial fullness or swelling. Intraorally, there was evidence of good oral hygiene with a stable occlusion. The right mandibular premolars and molars, including a fourth molar, were unrestored and without caries. No mobility was detected and no percussion sensitivity was reported. The right mandibular gingival and alveolar mucosa appeared normal without evidence of lingual or buccal bony expansion. A conventional panoramic image demonstrated a unilocular, poorly-corticated, 2.0 × 1.5 cm radiolucency affecting the periapical region from the second premolar to the second molar. (Fig 1) A subsequent medical CT identified slight thinning of the inferior and lingual cortex around the first molar. The differential for the primary finding of a well-defined radiolucency of the posterior mandible is quite broad, but favors reactive or benign neoplastic entities. The appearance of scalloping between the roots of the teeth supports this interpretation. In cases where the internal structure of a radiolucency suggests a reduced trabecular pattern (rather than multiloculations), medullary expansion and a possible hematopoetic origin could be considered. As a result, the differential diagnosis in the pediatric setting may include: odontogenic lesions such as an odontogenic keratocyst (OKC) and ameloblastoma; simple (traumatic) bone cyst; and lesions containing abundant histiocytes such as benign fibrous histiocytoma or Langerhans cell histiocytosis. OKCs are relatively common odontogenic lesions. They present most commonly in the posterior mandible and while a wide age range at presentation is recognized, they most frequently are identified in the second and third decades of life. Radiographically, small lesions may appear unilocular while larger lesions can appear multilocular.1,2 Scalloping of the borders is commonly seen. OKC may or may not be associated with an impacted tooth. In most cases, OKCs are asymptomatic without significant cortical expansion. Root resorption is relatively uncommon when compared to benign odontogenic neoplasms such as ameloblastoma3. Ameloblastomas are benign but locally aggressive tumors of odontogenic epithelium and represent the most common neoplasm of odontogenic origin.4 They present most commonly in the posterior mandible either as a unilocular or multilocular radiolucency and often show resorption of adjacent tooth roots.3 Unicystic lesions are more common in children than adults, however most of these cases are associated with an impacted tooth.5 The majority of cases are asymptomatic at presentation, with cortical expansion a common finding. Simple bone cysts are intraosseous cystic cavities lined by a fibrous membrane that are often empty at surgical entry or contain scant blood or serous fluid. They are most commonly seen in male patients under 20 years of age and are asymptomatic.6,7 They are far more prevalent in the mandible than in the maxilla, with predilection for the body of the mandible. Radiographically they demonstrate a well-defined, unilocular appearance, and have a characteristic scalloping around the roots of adjacent teeth, which test vital. Intraosseous benign fibrous histiocytomas of the jaws are argued to represent a wide array of lesions containing variable amounts of histiocytes.8 Within the literature, these lesions have been variably classified, such as the non-ossifying fibroma, which is classically seen in young patients in the metaphysis of long bones, xanthogranuloma, fibroxanthoma, and others. These lesions are most commonly seen in the second to third decade of life and have a slight male predominance.9 The majority present without symptoms or expansion. Radiographically, these lesions can be unilocular or multilocular, and often have a well-defined and sclerotic border. Langerhans cell histiocytosis is a rare hematologic neoplastic disease seen more frequently in children than adults. It is characterized by mutations in the MAPK pathway, with BRAFV600E mutations identified in about 50% of cases.10 There is a wide range of presentations, from solitary bone lesions to multi-system disease. Bony lesions affect the skull most commonly, and present as lytic lesions. Jaw involvement has been reported, which can range in appearance, from mimicking aggressive periodontal disease to benign periapical pathology.11,12 Isolated lesions in the jaws can appear as unilocular well-defined radiolucencies, mimicking periapical or residual cysts.13 An incisional biopsy of the right mandible was planned. At the time of surgery, a partially empty cavity was encountered with minimal bleeding. Soft tissue was thoroughly curetted from within the intrabony cavity, retrieved with a hemostat and submitted for histopathologic examination with a differential diagnosis of ameloblastoma, odontogenic keratocyst, traumatic bone cyst and aneurysmal bone cyst and central giant cell granuloma. Microscopic examination revealed a loosely-cellular fibrovascular connective tissue that contained numerous foamy mononuclear cells consistent with macrophages/histiocytes with areas of hemorrhage. Occasional lymphocytes and mast cells were identified with dispersed deposits of hemosiderin. (Fig 2A) Immunohistochemical analysis showed strong, uniform cytoplasmic expression of CD163 (Fig 2B) within the lesional cells with more limited expression of Factor XIIIa. Probes for S-100 and CD1a were negative. The diagnosis was benign fibrohistiocytic proliferation consistent with xanthoma of bone. The patient had an unremarkable post-operative course and was followed without additional therapy. During the follow-up period, a series of previous bitewing radiographs were recovered from the patient's records. The superior margin of a radiolucent lesion was first visible between the roots of the mandibular right first and second molars in an image obtained over 3 years prior to the patient's initial presentation to oral surgery. Comparison to the pre-treatment panorex indicated little to no change in this margin during that time. The patient presented 9.5 months post-operatively with no complaints and no sign of abnormality on extraoral and intraoral examination. A panoramic image revealed substantial return of normal bone trabeculation in the right posterior mandible. (Fig 3) Benign fibrohistiocytic lesions of the jaw have been reported using various terminology, including xanthoma of bone, primary intraosseous xanthoma, xanthogranuloma, xanthofibroma and fibrous xanthoma of bone. The term central xanthoma of the jaws (CXJ) was proposed in 2015 and described lesions that were dominated histologically by xanthoma cells without a significant storiform component more typical of benign fibrous histiocytoma.14,15 As in other skeletal sites, primary and secondary lesions have been described with the latter occurring in the setting of an associated endocrine/metabolic disorder. Associated traumatic bone cysts, aneurysmal bone cysts and benign fibro-osseous lesions have also been reported. In 2020, a series of 6 new and 35 previously-published primary cases was presented under the term primary intraosseous xanthoma of the jaws.16 The favored site was posterior mandible (36/41, 88%) with a mean age of 30 years and no gender predilection. Patients were typically asymptomatic and discovered as an incidental finding on radiographic imaging. Most cases presented as a well-defined, 1-2 cm radiolucency with variable cortication. Mewar and Foss recently reported on 50 cases of benign fibrohistiocytic lesions of the jaws that met their inclusion criteria.8 Within this group, 64% were designated as a form of fibroxanthoma, 26% as benign fibrous histiocytoma or fibrohistiocytic lesion and 10% as other forms of xanthoma. The posterior mandible was the favored site (92%) and the mean age at presentation was 29 years. A varied radiographic presentation was reported, ranging from a mottled or honeycomb appearance to predominantly radiolucent lesions with poorly defined borders. Cortical expansion was noted in some cases with occasional root displacement or resorption. Histopathologically, CXJ is characterized by variable proportions of admixed bland spindle cells and large, foamy or granular histiocytes. Storiform arrangements of the spindle cells may be identified but do not predominate the lesional tissue. Areas of hemorrhage, reactive bone and scattered chronic inflammation have also been reported. The xanthoma cells are strongly and uniformly positive for expression of CD68 and CD163 with variable expression of FXIIIa and are uniformly negative for expression of S-100 and CD1a.17 Treatment for CXJ has primarily relied upon conservative surgical removal, usually excisional biopsy and curettage. Local recurrence is considered unlikely, however, periodic radiographic follow-up is recommended with most cases showing evidence of resolution or normalization of the local bone within 1-2 years. [ABSTRACT FROM AUTHOR] |
Full Text from ScienceDirect