(1) Médico residente
(2) FEBOMS. Médico adjunto del Servicio de Cirugía Oral y Maxilofacial de Córdoba. Profesora asociada de la Facultad de Medicina de Córdoba
(3) Médico adjunto. Servicio de Cirugía Oral y Maxilofacial. Hospital Universitario "Reina Sofía" de Córdoba

Address:
Dra. Gracia M. Barrios Sánchez
Servicio de Cirugía Oral y Maxilofacial
Hospital Universitario Reina Sofía
Avda. Menéndez Pidal s/n
14004 Córdoba
E-mail: gracia_barrios@yahoo.es

INTRODUCTION

The inflammatory pseudotumor is a clinicopathologic term used to describe a rare, pseudoneoplastic and lymphoproliferative disorder that can appear in many different parts of the human body.

The etiology of the inflammatory pseudotumor continues to be unknown. Immunological and infectious causes have been postulated, such as the Epstein-Barr virus (1).

Clinically, inflammatory pseudotumor presents as a progressive space-occupying mass wich may be found at different locations. The lung is the most frequently affected organ (2,3). In the head and neck region, inflammatory pseudotumor has been described involving the orbits (4,5), the paranasal sinuses (6), the larynx, the pterygomaxillary space, and the oral cavity. However, it is infrequently found in the salivary glands. In fact, in the revised bibliography, only one case has been found at the submandibular gland (7), the rest of the cases described until now, in salivary glands, are related to the parotid gland (8,9). It may affect individuals of both sexes and of a wide range of ages.

Diagnosis is based on the histological examination of the lesions, which are mainly formed by four histological elements: histiocytes, myofibroblasts, plasma cells and lymphocytes. Although it is histologically a benign lesion, it can behave aggressively with local invasion, as a benign or malignant neoplasm, or as an infectious granulomatous disease. In this article, one case of inflammatory pseudotumor arising in the right parotid is reported.

CASE REPORT

A 48-year-old woman, without allergies or personal history of relevance, was referred to the Maxillofacial Surgery Department of our hospital because of a progressively growing tumour in her right infrauricular area which had lasted for one month, withouth any accompanying symptoms.

During the physical examination, a firm lesion, located in the right parotid gland, behind the mandibular ramus, measuring approximately 1.5 x 2 cm in diameter was detected. No signs of facial palsy were noted. The parotid duct remained permeable. No adenopathies were found.

Fine-needle aspiration biopsy revealed a possibly malignant epithelial tumour. Ultrasonography of the parotid gland showed a poorly defined hypoechoic lesion, measuring approximately 16 mm in diameter and with a cystic area inside.

CT scan showed a well-defined rounded low-attenuation lesion with central necrosis, highlighted by the contrast, within the right parotid gland (figure 1).

Once the cytological diagnosis had revealed a possibly malignant epithelial tumour, the patient was scheduled for surgical treatment. A total right parotidectomy was planned. During surgery, a hard nodular lesion was detected. This lesion was whitish in appearance and was attached to the facial nerve trifurcation. Because of its attachment to the facial nerve and the preoperative cytological results, two intraoperative biopsies were taken. They revealed non-malignancy, and after this a total removal of the affected gland preserving the facial nerve was he choice of treatment.

Microscopical study of the surgical specimen (figures 2 and 3) showed a lymphoid cell material, without signs of atypia and with small irregularly fused areas. Focal diastase resistant PAS + material was found. Immunohistochemical techniques showed positivity for actin, negativity for p53 and positivity for k167.

The perilesional gland did not show significant alterations.

This fidings lead to the conclusion that the lesion was an inflammatory pseudotumor of the parotid gland. The postoperative evolution of the patient was good , without complicaions or paralysis of the branches of the facial nerve and no recurrence after five years.

DISCUSSION

Inflammatory pseudotumor is a term that refers to a rare benign lymphoproliferative disorder with characteristic histopathological features and that can appear anywhere in the human body. It was first described in 1939 by Brunn. It affects individuals of both sexes and of a wide range of ages.

The exact nature of this disorder and how it should be classified are still unknown. The different terms that have been used to name these types of lesions show the poor understanding of the subject. Thus, various terms have been used, such as: fibrous histiocytoma, fibrous xanthoma, inflammatory myofibroblastic tumour, inflammatory myofibrohistiocytic tumour, myofibroblastoma, plasma cell granuloma, inflammatory pseudotumor, etc. All these terms are based on histopathological findings (10).

In 1978, Somersen describes three histopathological types of inflammatory pseudotummors (10), although most lesions contain elements of all types. These are:

- Histiocytic type, called xanthogranuloma.

- Plasma cell type, called plasma cell granuloma.

- The sclerotic or sclerosing granulomatous type.

Histologically, the lesions contain four essential components: histiocytes, myofibroblasts, plasma cells and lymphocytes. The results of immunohistochemical studies show a population of cells of two types: myofibroblats and histiocytes revealing positivity for actin, vimentin and KP1 (CD3). These findings support the theory that the inflammatory pseudotumor is a lesion of a fibroinflammatory nature (8).

Clinically, it presents as a progressive space-occupying mass whose symptomatology depends on its location. The lung is the most frequently affected organ, followed by the upper digestive tract and the ganglionar system (12). At the head and neck level, cases have been described involving the orbits causing proptosis, chemosis, orbital pain, erythema and limitation of the movements of the globe (10).

Manifestations in the larynx can cause hoarseness, stridor and airway obstruction. In addition, cases have been found where the maxillary sinus, the rhinopharynx or the thyroid gland have been affected. As far as salivary glands are concerned, most of the cases described until now involve the parotid gland (8,9) and only one case has been found affecting the submandibular gland. At the parotid level, it manifests as a hard nodular lesion with occasionally associated lymphadenopathies, without facial nerve involvement (9).

The exact diagnosis is difficult and it is often made by exclusion, so that it has sometimes required more than one biopsy or the surgical removal of the lesion, in order to confirm the absence of neoplasm or infection, and to be able to establish the diagnosis of inflammatory pseudotumor, as it occurred in the case described in this article.

CT scan usually shows a well-circumscribed apparently inflammatory lesion which can present central necrosis. Bone erosion is rare but possible.

Prognosis is generally good, but despite being a benign lesion histologically, there are some cases of agressive behaviour and local invasion (13).

In cases where the parotid gland is affected, the differential diagnosis includes obstructive sialadenitis, other non-specific inflammatory disorders and parotid tumours.

There is no unanimous agreement on the most appropiate treatment. In many cases, surgical treatment is needed since the histological study of the surgicalpiece will establish definitely the correct diagnosis. The type of surgery depends on the location and extent of the disease, but in general a complete removal of the space-occupying mass is carried out.

Other terapeutic procedures used include: radiotherapy, chemotherapy, azathioprine, indomethacin and steroids. Steroids rapidly reduce the symptoms caused by the edema, but their effect on the primary process has not been proven (3,12).

In this particular case, we suggested a surgical treatment with complete removal of the entire gland, and an accurate diagnosis could only be established after the histological examination of the intraparotid tumour.

In conclusion, the inflammarory pseudotumour is a rare disease that can affect any organ and that is often clinically suspicious of neoplasm or infection. It is important to establish a correct diagnosis since its prognosis after treatmnet is excellent. As far as the parotid gland is concerned, the greatest difficulty arises from the initial cytological diagnosis by fine-needle aspiration, since in most cases the result is suspect of malignancy which leads to a total parotidectomy and, on occasions, the removal of the facial nerve. In the case described here, two intraoperative biopsies were needed to exclude malignancy. And even so, the true diagnosis was obtained only after having analysed the surgical specimen.

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