Caso Clínico

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Maxillary brown tumor: A diagnostic tool for primary hyperparathyroidism

Tumor pardo maxilar: Elemento diagnóstico de hiperparatiroidismo primario

 

S. Gallana Álvarez¹, C.I. Salazar Fernandez², F.J. Avellá Vecino³, J. Torres Gómez⁴, J.M. Pérez Sanchez⁵

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Abstract: The primary hyperparathyroidism is a generalized disorder of the osseous metabolism, caused by hypersecretion of PTH. Hyperparathyroidism has a multiple etiology. In its primary form, the hypersecretion of the hormone is caused by the gland itself, the commonest reason being parathyroid adenoma. The treatment of first choice for brown tumor is the parathyroidectomy because the normalization of parathyroid function should lead to a reduction in size or disappearance of the tumor. We present a case of the brown tumor in the mandible and primary hyperparathyroidism in whom the tumor enlarged after removal of parathyroid adenoma. Upon presentation of this report, our aim is to bring forward the significance oral manifestations of systemic pathology has for oral and maxillofacial surgeons. Key words: Hyperparathyroidism; Brown tumor; Maxilla.

Resumen: El hiperparatiroidismo primario es un transtorno generalizado del metabolismo óseo producido por un aumento de la secreción de hormona paratiroidea (PTH). La etiología de este transtorno es múltiple; en la forma primaria la causa de la hipersecreción de la hormona es la propia glándula, y el motivo más frecuente el adenoma paratiroideo. Los tumores pardos son lesiones óseas focales secundarias a hiperparatiroidismo. El tratamiento de elección de los tumores pardos es la extirpación del adenoma de paratiroides, ya que la normalización de la función paratiroidea debería provocar una reducción del tamaño o desaparición del tumor. Presentamos un caso de tumor pardo mandibular en un paciente con hiperparatiroidismo primario, en el cual el tumor recidivó después de la extirpación del adenoma paratiroideo. La finalidad de la presentación de este caso es recordar el interés que para el cirujano oral y maxilofacial representan las manifestaciones orales de la patología sistémica. Palabras clave: Hiperparatiroidismo; Tumor pardo; Maxila.

Recibido: 13 de diciembre de 2004

Aceptado: 25 de mayo de 2005

 

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1 Médico residente. Servicio de Cirugía Oral y Maxilofacial.
2 Médico adjunto. Servicio de Cirugía Oral y Maxilofacial.
3 Médico especialista de Cirugía Oral y Maxilofacial.
4 Médico especialista de Anatomía Patológica.
5 Jefe de Servicio. Servicio de Cirugía Oral y Maxilofacial.
Hospital Universitario Virgen Macarena. Sevilla. España.

Correspondencia:

Silvia Gallana Álvarez.
c/ Isbilia Nº10
41907 Valencina de la Concepción. Sevilla, España.
E-mail: sgallana@hotmail.com

 

Introduction

Hyperparathyroidism has been defined as a metabolic condition that produces an increase in the secretion of the parathyroid hormone (PTH). The basic function of this hormone is the metabolic control of calcium.¹

The hypersecretion of PTH is characterized by hypercalcemia, hypophosphatemia and abnormal bone metabolism. Hypercalcemia is the key for diagnosing this disease and it represents the most important metabolic feature.²

The etiology of hyperparathyroidism is multiple; the primary form is normally due o a benign functioning tumor (parathyroid adenoma) of one of the four parathyroid glands, that produces excess hormone.³

Bone disorder by hyperparathyroidism is called Osteitis Fibrosa Cystica and it was first described in 1891 by Von Recklinghausen. Of the manifestations of this disease, brown tumors represent an example of a focal lesion.^2,5,6

Brown tumors are considered a reparative lesion of giant cells, and their appearance is of an osteolytic lesion, that is generally multilocular, well-defined and with thinning of cortical bone.^2,4 In these cases the differential diagnosis is important and it should include other giant cell lesions that affect the maxillae.

Brown tumors can appear in any part of the skeleton and when they appear in the head and neck they generally affect the mandible. Here we generally find a reduction in radiographic density, demineralization of the lower mandibular border and of the lower dental arch, as well as a thinning of the cortical rims of the maxillary sinuses.^7,8 Brown tumors have also been described in other areas of the face including the orbital region.^9,10

While most authors agree that the initial treatment for primary hyperparathyroidism should be the removal of the diseased parathyroid gland, causing the regression of bone lesions, others have combined a parathyroidectomy with curettage and an enucleation of mandibular lesions.^9,11,12 Despite the current analytical techniques available, and that patients with parathyroidism tend to be diagnosed at an early stage of the disease before the appearance of bone lesions, we should bear in mind the possibility of coming across late diagnoses with extensive bone involvement.^9,13

Clinical case

A 31-year-old male, with a medical history of tension headaches, over the previous months and a gastric ulcer was referred to our Service by his dentist in June 2000, as he had repeated episodes of inflammation of the lower right maxilla and a radiotransparent x-ray image of the right mandibular angle in the areas of teeth numbers 47 and 48. The radiological examination carried out by our Service (orthopantomography) detected a cystic lesion that was osteolytic and multilocular, with clear well-defined borders and located in the lower maxilla. It was affecting teeth numbers 47 and 48 (fig. 1).

A biopsy was carried out of the lesion and the result was of a reparative granuloma of giant cells. Later, in July 2000, surgical treatment was carried out on the lesion by means of curettage and bone fill.

The anatomopathologic study of the lesion described it as a dense fibroblastic stroma, containing numerous giant cells that had hemorrhagic areas, with macrophages with hemosiderin pigment, that established the diagnosis of reparative granuloma of giant cells (fig. 2).

Given the nature of the lesion, an analytical profile of the phosphocalcic metabolism was requested and by means of the tests a PTH level was discovered of 101mg/dl (n: 10-65), Calcium 11 mg/dl (n: 8.5-10.5) and phosphate 2.3 mg/dl (n: 2.5-4.5). As a result of this, the diagnosis was established of brown tumor with hyperparathyroidism and he was sent to the Endocrinology Service in January 2001 for evaluation. A thyroid function test was requested together with a thyroid/parathyroid ultrasound as well as a gammagraphy of the parathyroid glands. The thyroid function test was normal. The imaging test by means of ultrasound did not show any lesion, nor an increase in the size of the parathyroid glands. The results of the thyroid gammagraphy showed a parathyroid adenoma in the lower right gland (fig. 3). With this diagnosis he was sent to the General Surgery Service for its surgical removal.

While the patient was waiting for surgical treatment, he was monitored periodically in our unit, and correct ossification in his jaw was observed (fig. 4).

In February 2003 the parathyroid lesion was operated on. After the removal of the parathyroid adenoma, his progress was monitored and a mandibular recurrence of the lesion was discovered (fig. 5) and a decision was taken to excise this again surgically in October 2004. Although the followup period is short, his progress postsurgery has been good.

Discussion

The incidence of primary hyperparathyroidism is around 0.1%. It is between two and three times more common in the female sex and it is observed particularly in the 3^rd and 6^th decades in life.^3,4 The most common cause of primary hyperparathyroidism is parathyroid adenoma (81%), followed by glandular hyperplasia (15%), with parathyroid carcinoma appearing only in 0.4-0.5 % of cases.⁹

The clinical manifestations of the disease cover a fairly wide range, but most patients present signs and symptoms as a result of renal stones, peptic ulcers, psychiatric problems and pain associated with bones and joints. In our case, the patient had a background of asthenia and a gastric ulcer. However, authors such as Suarez-Cunqueiro⁷ and Udelsman¹⁴ report cases of patients that were asymptomatic at diagnosis.

The incidence of bone lesions with regard to hyperparathyroidism has fallen from 80% to a current 15%,² a reduction that is attributed to better hypercalcemia monitoring in patients that are asymptomatic and to biochemical studies becoming generalized. In spite of this, Dilip and cols.,⁵ reported a series of 40 cases that all had generalized bone involvement.

Within the osseous manifestations of hyperparathyroidism there are brown tumors that appear in approximately in 10% of cases and in advanced stages of the disease.^15,16 They can appear in any part of the skeleton but it is more common for them to appear on the ribs, clavicle and pelvis. Mandibular involvement has been registered in 4.5% of patients.⁷ As a result of the direct effect of the PTH on bones, a conversion occurs of the osteogenic potential of the cells, turning them from osteoblasts to osteoclasts, with bone resorption predominating over the formation of new bone tissue. In this way an osteoid tissue is formed within fibroblastic vascular tissue, in a failed attempt at forming bone trabeculae.⁵ As a result of intraosseous bleeding and of tissue degeneration, cysts may develop; groups of hemosiderin-loaded macrophages, giant cells and fibroblast fill these cystic lesions. Vascularization, hemorrhages and hemosiderin deposits give the brown characteristics of the lesions and the term brown tumors.^5,7

It is important to point out that brown tumors are non-neoplastic lesions and that they are very similar to giant cell tumors, but in the context of hyperparathyroidism they are considered reparative granulomas and they do not have the malignant or neoplastic potential of real giant cell lesions.^18,19 The symptomatology caused by these lesions depends on their size and location. In the mandible they can cause pain or deformity, as well as alterations in mastication, as occurred in the clinical case presented. In other cases, such as the one presented by Fdez.-Bustillo and cols.,² the lesion was asymptomatic and the diagnosis was accidental as a result of a radiological examination.

When a tumor of the mandible has been diagnosed as a giant cell tumor, hyperparathyroidism should be ruled out by means of tests otherwise we could be before a brown tumor. Other differential diagnoses include the reparative granuloma of giant cells, giant cell tumors, fibrous displasia and aneurismatic bone cyst. The definitive diagnosis is only possible if the clinical, radiological and analytical findings are compared.¹¹

There is agreement as to the treatment of choice for primary hyperparathyroidism being a parathyroidectomy, however opinions are divided as to the treatment for bone lesions. Authors such as Scott and cols.,¹² believe that bone lesions reappear spontaneously following removal of the diseased parathyroid gland; Others such as Mtnez-Gavidia and cols.,²⁰ recommend initial treatment with systemic corticoids in order to reduce the size, followed by surgical removal of the residual lesion. In any case, where there are large destructive cysts, the amount of tissue damaged may be so large that there are few possibilities of remodeling once normocalcemia has been acieved.⁷ In these situations, and when the lesions continue for more that six months, and there is interference with the affected organ, or there is even growth despite adequate metabolic control, Daniels and cols.,⁹ and Yamazaki and cols.,¹¹ recommend curettage and enucleation. In our case due to the lesion recurring seven months later in spite of a parathyroidectomy, surgical treatment was decided on (enucleation and curettage) in October 2004 with the patient currently being asymptomatic.

Conclusions

Due to there currently being an improvement in analytical techniques, the diagnosis of hyperparathyroidism is carried out when the disease is in an asymptomatic phase, although finding patients with advanced bone lesions still exists. In all giant cell lesions the existence of primary hyperparathyroidism should be ruled out.

The treatment of first choice for bone lesions is a parathyroidectomy; however in larger lesions, or in those that are persistently growing in spite of treatment or if the lesions is causing incapacity, curettage and associated enucleation should be carried out

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