Maxillary Brown Tumor Unveiling Primary Hyperparathyroidism: A Rare Diagnostic Challenge

ABSTRACT

Maxillary brown tumors are rare and may mimic malignant or odontogenic lesions, posing a diagnostic challenge. This case highlights that isolated facial swelling may be the first manifestation of primary hyperparathyroidism and underscores the importance of biochemical screening to prevent misdiagnosis and unnecessary surgery.

1. Introduction

Primary hyperparathyroidism (PHPT) is a common endocrine disorder characterized by autonomous overproduction of parathyroid hormone (PTH), most often due to a solitary parathyroid adenoma in approximately 85% of cases [1]. This leads to hypercalcemia and a spectrum of clinical manifestations, including renal stones, bone pain, and gastrointestinal symptoms. Among the skeletal complications, osteitis fibrosa cystica represents a severe form of bone disease, marked by accelerated osteoclastic resorption, fibrous replacement, and cystic changes [2].

Brown tumors, a hallmark of advanced osteitis fibrosa cystica, are benign, focal osteolytic lesions composed of multinucleated giant cells, fibrous stroma, and hemosiderin deposits, resulting from chronic PTH excess [3]. These lesions occur in 1.5% to 4.5% of PHPT cases and are more frequent in long bones such as the femur, pelvis, and ribs, with a predilection for patients over 50 years and a three‐fold higher incidence in women [4, 5]. Involvement of the maxillofacial region is rare, accounting for about 4.5% of brown tumors, and typically affects the mandible more than the maxilla [4, 6]. When present in the maxilla, brown tumors often manifest as painless swellings that can mimic malignant neoplasms, odontogenic cysts, or giant cell tumors, leading to diagnostic delays and potential mismanagement [7, 8].

This report describes an unusual case of a solitary maxillary brown tumor as the initial presentation of PHPT in a 50‐year‐old woman. It is distinguished because of a solitary maxillary brown tumor being the first and only clinical manifestation of primary hyperparathyroidism, a presentation that is exceedingly rare and diagnostically challenging in otorhinolaryngologic practice. It underscores the diagnostic challenges in an otorhinolaryngologic context and the value of integrating biochemical investigations with imaging for accurate diagnosis.

2. Case History

A 50‐year‐old female patient presented to the otorhinolaryngology department with a five‐month history of progressive, asymptomatic swelling on the right side of her face. The swelling had a slow onset and was not associated with pain, fever, nasal obstruction, epistaxis, trismus, or difficulties in mouth opening or chewing. She reported non‐specific bone pain and muscle cramps over the preceding few months but denied any significant past medical history, family history of endocrine disorders, or relevant comorbidities. The patient was from a low socioeconomic background with limited access to healthcare resources.

On physical examination, a diffuse, non‐tender swelling measuring 5 cm by 4 cm was noted on the right face, extending from the nasal ala to the cheek, superiorly to the infraorbital rim, and inferiorly to the oral commissure. The lesion was soft to firm in consistency, immobile, and non‐fluctuant, with intact overlying skin. Intraoral examination revealed poor oral hygiene, multiple missing teeth, and a firm, non‐tender bulge on the right hard palate extending posteriorly to the soft palate junction, without mucosal erythema, ulceration, or hyperemia (Figure 1). Tongue movements and gag reflex were normal, and no cervical lymphadenopathy was detected.

FIGURE 1.

Right‐sided facial swelling seen from (a) frontal view and (b) right lateral view. (c) The intraoral right‐sided bulge of the hard palate with loss of multiple upper teeth.

3. Differential Diagnosis, Investigations, and Treatment

Initial laboratory investigations showed elevated albumin‐corrected serum calcium (13.5 mg/dL; reference range 8.5–10.5 mg/dL), hypophosphatemia (serum phosphate 2.1 mg/dL; reference range 2.5–4.5 mg/dL), and markedly elevated intact parathyroid hormone (PTH 1034 pg/mL; reference range 15–65 pg/mL). Serum albumin was within the normal range, and calcium values were interpreted as albumin‐corrected calcium. Other routine blood tests, including complete blood count, renal function, and liver function, were within normal limits. Measurement of serum 25‐hydroxyvitamin D was not performed because of financial constraints and limited laboratory resources. There was no clinical or radiologic evidence of nephrolithiasis or nephrocalcinosis. Furthermore, genetic analysis was not performed in this patient, as there were no clinical features suggestive of a hereditary hyperparathyroidism syndrome, and the patient had no family history of hyperparathyroidism, jaw tumors, renal lesions, or endocrine neoplasia.

Neck ultrasonography demonstrated an enlarged right thyroid lobe (TIRADS category 3) and a hypoechoic mass adjacent to the right inferior thyroid pole, suggestive of a parathyroid lesion. Technetium‐99 m sestamibi (99mTc‐MIBI) scintigraphy confirmed increased radiotracer uptake in the right inferior parathyroid region at 20 and 40 min, consistent with a parathyroid adenoma (Figure 2). Computed tomography (CT) of the face and neck revealed a well‐demarcated osteolytic lesion measuring 5.4 cm by 4.6 cm in the right maxilla, with cortical expansion and thinning, but no evidence of invasion into adjacent structures. On the basis of the clinical presentation, biochemical profile, and imaging findings, a diagnosis of brown tumor secondary to primary hyperparathyroidism was suspected. Bone mineral density assessment by dual‐energy X‐ray absorptiometry (DXA) was not performed because of patient financial constraints and limited access to resources. No biopsy of the maxillary lesion was performed, as the clinical and investigative features were highly indicative, and surgical intervention for the underlying cause was prioritized.

FIGURE 2.

99mTc sestamibi scan showing increased radiotracer uptake at the right inferior parathyroid gland at 20 min and 40 min.

The patient underwent right hemithyroidectomy and parathyroidectomy under general anesthesia. Hemithyroidectomy was performed because of the presence of an enlarged right thyroid lobe (TIRADS 3) closely adherent to the parathyroid adenoma, which limited safe intraoperative dissection and obscured clear identification of tissue planes. Concomitant thyroid lobectomy was therefore undertaken to ensure complete excision of the parathyroid adenoma, avoid capsular rupture, and minimize the risk of residual disease or recurrent laryngeal nerve injury. Intraoperative findings confirmed a right inferior parathyroid adenoma, which was excised. Histopathological examination of the resected parathyroid tissue verified the diagnosis of a benign parathyroid adenoma. The procedure was uneventful, with no intraoperative complications.

4. Conclusion and Results

Postoperatively, biochemical parameters normalized rapidly: PTH decreased to 7 pg/mL, serum calcium to 8.6 mg/dL, and serum phosphate to 1.8 mg/dL. The patient experienced no complications during recovery and was discharged on calcium and vitamin D supplementation as per standard protocol. At two‐month follow‐up, clinical examination demonstrated a substantial reduction in the facial swelling, confirming regression of the brown tumor following removal of the hyperparathyroid stimulus (Figure 3). Because of resource constraints and the patient's socioeconomic status, no follow‐up imaging was performed. The patient reported satisfaction with the outcome and resolution of her bone pain and muscle cramps.

FIGURE 3.

The mostly resolved facial swelling at 2‐months follow‐up.

5. Discussion

PHPT arises from excessive PTH secretion, typically from a solitary adenoma, leading to dysregulated calcium homeostasis and multisystem effects [1]. In this case, the patient's presentation with a solitary maxillary brown tumor exemplifies a rare skeletal manifestation of advanced PHPT, where chronic PTH elevation induces osteoclastic hyperactivity, peritrabecular fibrosis, and localized bone destruction [2]. Compared with previously reported cases, the present case follows a diagnostic pathway in which an isolated maxillary lesion initially raised concern for malignancy, with definitive diagnosis established only after biochemical evaluation and parathyroid localization, and management consisting solely of parathyroidectomy without maxillofacial intervention. Brown tumors develop as reparative granulomas filled with multinucleated giant cells and hemosiderin‐laden macrophages, reflecting the hemorrhagic and cystic changes of osteitis fibrosa cystica [3]. From an endocrinological perspective, this process stems from PTH‐mediated activation of receptor activator of nuclear factor kappa‐B ligand (RANKL), which promotes osteoclast differentiation and bone resorption, compounded by secondary hypophosphatemia and hypercalcemia [9].

The diagnostic approach in PHPT emphasizes biochemical confirmation, with elevated serum calcium, low phosphate, and markedly raised PTH levels, as observed here [10]. Preoperative localization via ultrasonography and 99mTc‐MIBI scintigraphy is standard, facilitating targeted parathyroidectomy [10]. In this patient, the maxillary lesion's osteolytic appearance on CT raised suspicions of malignancy or odontogenic pathology, a common diagnostic pitfall in maxillofacial presentations of brown tumors [11]. Assessment of serum 25‐hydroxyvitamin D was not available in this patient because of socioeconomic and resource limitations. Although vitamin D deficiency may coexist with primary hyperparathyroidism and influence PTH levels, the markedly elevated PTH concentration, albumin‐corrected hypercalcemia, and localization of a parathyroid adenoma were sufficient to establish the diagnosis [10, 12, 13]. Postoperative normalization of calcium and PTH further supports primary hyperparathyroidism as the underlying etiology [13]. The decision to forgo biopsy aligned with guidelines, as histological findings often mimic giant cell tumors, and definitive diagnosis relies on correlating imaging with endocrine abnormalities [4]. This case highlights the endocrinologist's role in integrating metabolic evaluation to avoid unnecessary invasive procedures, particularly in resource‐constrained settings where follow‐up imaging may be limited. Bone mineral density assessment by DXA, which is recommended for skeletal evaluation in primary hyperparathyroidism, was not available in this patient because of socioeconomic constraints. Nevertheless, the presence of a brown tumor represents advanced skeletal involvement and, in itself, indicates significant bone disease. Surgical management was therefore clearly indicated regardless of formal BMD assessment.

A possible differential diagnosis was hyperparathyroidism–jaw tumor syndrome (HPT‐JT), caused by germline mutations in the CDC73 gene. It typically presents at a younger age, is often associated with multiglandular disease or parathyroid carcinoma, and is characterized by ossifying fibromas of the jaw that do not regress after parathyroidectomy [14, 15]. In contrast, the present case involved a solitary parathyroid adenoma and demonstrated postoperative regression of the maxillary lesion, findings that are characteristic of a brown tumor in sporadic primary hyperparathyroidism rather than a hereditary syndrome [13]. Further differential diagnosis of brown tumors is broad and includes both malignant and benign osteolytic conditions. Malignant entities include bone metastases, osteosarcoma, and multiple myeloma, whereas benign lesions encompass giant cell tumor and its maxillofacial counterparts, such as central giant cell granuloma, aneurysmal bone cyst, cherubism, fibrous dysplasia, cemento‐osseous dysplasia, and other fibro‐osseous lesions [16]. Radiologically and histologically, brown tumors may closely mimic these entities, particularly giant cell–rich lesions, making isolated interpretation misleading in the absence of biochemical correlation. Contemporary endocrine literature emphasizes that the distinction relies on integrating imaging findings with serum calcium, phosphate, and parathyroid hormone levels, rather than histopathology alone, to avoid misdiagnosis and unnecessary aggressive surgery [16, 17].

Management of PHPT focuses on surgical excision of the adenoma, which normalizes PTH and calcium levels, halting bone resorption and promoting lesion remineralization [5]. Post‐parathyroidectomy, the patient's rapid biochemical resolution and clinical regression of the swelling at 2 months underscore this conservative approach for brown tumors, obviating the need for maxillofacial intervention [18]. In endocrinology practice, postoperative monitoring includes serial calcium and PTH assessments to prevent hypocalcemia, with vitamin D and calcium supplementation as needed [10]. The absence of complications and sustained improvement in this case affirm the efficacy of this strategy, even without radiographic confirmation of tumor regression due to socioeconomic barriers. The complete clinical regression of a large maxillary lesion following parathyroidectomy alone, without biopsy or maxillofacial surgery, further underscores the distinctiveness of this case and supports a conservative, endocrinology‐first approach when biochemical findings are diagnostic.

Although focused parathyroidectomy is the standard surgical approach in primary hyperparathyroidism, concomitant hemithyroidectomy may be indicated when a thyroid lobe is enlarged, nodular, or densely adherent to the pathological parathyroid gland. In the present case, preoperative ultrasonography demonstrated right thyroid lobe enlargement, and intraoperatively, the adenoma was closely associated with the thyroid tissue. Hemithyroidectomy was therefore required to facilitate safe dissection, ensure complete adenoma removal, and reduce operative risk [13]. Following this, the patients are at increased risk of hungry bone syndrome after parathyroidectomy due to rapid skeletal remineralization. Prophylactic calcium and vitamin D supplementation with close postoperative biochemical monitoring is essential to prevent this complication [10, 13].

Brown tumors in PHPT are uncommon, occurring in 1.5%–4.5% of cases, with maxillofacial involvement in approximately 4.5% and a mandibular predominance [4, 6]. A systematic review by Brabyn et al. identified 45 cases of jaw brown tumors (mandible or maxilla) associated with hyperparathyroidism up to 2016 [4]. An updated literature search through PubMed, extending to November 2025, reveals additional reports, bringing the total to over 70 documented cases for jaw involvement, with at least 27 specifically detailing maxillary lesions in primary PHPT [8, 19, 20]. These cases often describe diagnostic delays because of mimicry of neoplasms, with most resolving post‐parathyroidectomy, similar to the present report [7, 21]. Recent case reports have similarly highlighted the diagnostic challenge posed by isolated maxillofacial brown tumors mimicking malignant or odontogenic lesions, with definitive diagnosis achieved only after biochemical confirmation of primary hyperparathyroidism and successful resolution following parathyroidectomy [22]. The solitary maxillary presentation here, without multifocal skeletal involvement, adds to the rarity and emphasizes the need for heightened endocrine suspicion in isolated facial swellings, especially in middle‐aged women. Unlike most reported cases, which describe multifocal skeletal involvement or mandibular predominance, this patient presented with an isolated maxillary lesion and no radiologic evidence of other skeletal brown tumors. Furthermore, the maxillary mass constituted the initial trigger for medical evaluation, rather than being detected after a known diagnosis of hyperparathyroidism. This clinical sequence remains infrequently reported in the literature.

This case contributes to medical knowledge by illustrating an unexpected presentation of PHPT in an otorhinolaryngologic context, highlighting educational merits for interdisciplinary collaboration between endocrinologists and surgeons. It underscores the importance of prompt biochemical screening to prevent progression to severe osteitis fibrosa cystica and advocates for adapted protocols in low‐resource environments. This case is notable for its isolated maxillary presentation, diagnostic ambiguity in an otorhinolaryngologic setting, and successful non‐maxillofacial management, contributing meaningful clinical insight to the limited body of literature on jaw brown tumors in primary hyperparathyroidism.

Author Contributions

Abdur Rehman: project administration, writing – original draft, writing – review and editing. Haitham Akaash: investigation, methodology, supervision. Javeria Awan: data curation, methodology, writing – review and editing. Sundas Masood: data curation, methodology, writing – original draft. Rahmat Gul Omarzai: methodology, writing – review and editing.

Funding

The authors have nothing to report.

Ethics Statement

The authors have nothing to report.

Consent

Written informed consent has been obtained from the patient for the collection of data and publishing it in the journal.

Conflicts of Interest

The authors declare no conflicts of interest.

Rehman A., Akaash H., Awan J., Masood S., and Omarzai R. G., “Maxillary Brown Tumor Unveiling Primary Hyperparathyroidism: A Rare Diagnostic Challenge,” Clinical Case Reports 14, no. 2 (2026): e72041, 10.1002/ccr3.72041.

Data Availability Statement

The data are available upon reasonable request.