Submaxillary gland mucocele: presentation of a case
Mucocele de la glandula submaxilar: a propósito de un caso

 

Fernando Boneu Bonet ⁽¹⁾, Enric Vidal Homs ⁽¹⁾, Aránzazu Maizcurrana Tornil ⁽²⁾, Javier González Lagunas ⁽³⁾

(1) Médico adjunto. Unidad de Cirugía Oral y Máxilo-Facial. Hospital L'Esperit Sant. Santa Coloma de Gramanet
(2) Médico Interno Residente. Servicio de Cirugía Oral y Máxilo- Facial.Hospital Universitario Valle Hebrón
(3) Médico adjunto. Servicio de Cirugía Oral y Máxilo-Facial. Hospital Universitario Valle Hebrón. Barcelona (España)

Address:
Dr. F. Boneu Bonet
C/ Provença 244, Esc A, 3º-2ª 08008 - Barcelona (España)
Tfno.: 93 - 4535692
Fax: 973 - 283143
E-mail: fboneu@teleline.es

Received: 6-10-2003. Accepted: 20-06-2004

 

 

INTRODUCTION

The term mucocele is referred to two concepts: the extravasation cysts resulting from salivary glandular duct rupture, with mucin leakage into the surrounding peri - glandular soft tissue, and the retention cysts, caused by a glandular duct obstruction and resulting in a decrease or even an absence of glandular secretion (1).

Mucocele can not be considered as a true cyst because its wall lacks an epithelial lining.

These lesions are very common in the minor salivary glands (particularly in the labial glands), but are very infrequent in the major salivary glands - including the submaxillary glands (1,2-6).

The present study describes a clinical case of a right submaxillary gland mucocele resolved by surgical treatment and reviews the differential diagnosis with other clinical entities.

CASE REPORT

A 25-year-old male was referred to the Oral and Maxillofacial Surgery Unit L'Esperit Sant Hospital (Santacoloma de Gramanet. Barcelona, Spain) with a soft tumor mass located in the right submaxillary region. The lesion had been present for the previous six months and showed inflammatory episodes or fluctuations in size, without pain and unrelated to food ingestion. The clinical history was otherwise unremarkable.

The physical examination revealed a soft, non-reducible right submandibular mass. The lesion was well circumscribed, painless, slightly mobile and measured about 2-3 cm in diameter. Bimanual palpation yielded the same information, the oral cavity findings being normal, with normal right Wharton's duct salivary flow. The mandibular branch of the facial nerve was unaffected, and no other alterations were noted.

Orthopantomography of the lesion afforded no information, while computed tomography (CT) showed the presence of an elongated mass anterior to the right submandibular gland, of a cystic appearance and measuring about 3 cm in greater diameter. The lesion was located anterior to the submandibular gland, lateral to the genioglossal muscle and medial to the mylohyoid muscle. No separating tissue plane was observed between the submaxillary gland and the contact surface of the mass, though a radiologically manifest separation was identified between the lesion and the rest of the neck structures. The density of the lesion was approximately 40 HU, compatible with the presence of a high protein content or some prior complication (Fig. 1). Following contrast injection, the lesion wall showed minimally enhanced uptake, suggestive of some previous infectious or bleeding episode. There was no evidence of lithiasis either in Wharton's duct or within the gland. The differential diagnosis contemplated a salivary cyst or mucocele. No communication was observed between the cervical mass and the sublingual space, as a result of which a cervical ranula was discarded.

The cystic lesion was removed under general anesthesia, together with a right Submaxillectomy (Fig. 2).

The histological study of the surgical piece revealed a cystic wall lacking an epithelial lining, with granulation tissue and abundant foam cells within the wall. This picture was considered to be compatible with a submaxillary gland mucocele (Fig. 3).

The patient was discharged 24 hours after surgery, and remains asymptomatic. Periodic controls are programmed in the outpatient clinic.

DISCUSSION

In patients with a neck tumor mass, the diagnostic protocol in our center contemplates the performance of imaging studies (orthopantomography, CT, magnetic resonance imaging) and fine needle aspiration biopsy (FNAB). The differential diagnosis centers on those lesions which manifest as cystic masses in the submandibular region and are of congenital origin (branchial cyst, dermoid/epidermoid cyst, thyroglossal cyst and cystic hygroma) or acquired origin (mucocele, salivary duct cyst, sialocele, pneumatocele, plunging ranula, abscesses and cystic degeneration of a tumor mass) (1, 2).

Cystic lesions of the submaxillary gland are infrequent. A review of four large series comprising 504 submandibular tumors revealed only three cysts (1,3,4), while a review of the Anglo-Saxon literature yielded only 5 submaxillary mucoceles (1,2,5,6). In the review conducted by Valldosera of 47 tumors (64% benign), no cystic lesions were found (7).

Submandibular gland mucoceles must be differentiated from other cystic lesions of salivary origin that can also develop in this region (Table 1). Anatomically, both plunging ranula and submaxillary mucoceles can occupy the submandibular space, and it is clinically impossible to distinguish between them. In such cases CT is useful for establishing a diagnosis and may identify the so-called "nail image", which is pathognomonic of cervical ranula. This sign corresponds to an extension between the lesion and the sublingual gland and can be observed in the posterior margin of the mylohyoid muscle or a dehiscence of the latter (8,9). When this image is missing and a mucocele is identified in intimate contact with the submaxillary gland parenchyma, the origin should be presumed to be submaxillary (6).

The differential diagnosis should also include other cystic lesions of different origins (Table 2). In such cases, the differential diagnosis can be established by CT and FNAB (9,10) However, the possibility of establishing a differential diagnosis with CT is conditioned by the relative density of the submandibular lesion: many epithelial tumors are radiologically homogeneous and present a density close to that of muscle; i n contrast, other epithelial tumors are not homogeneous and present necrotic and calcified areas. All such lesions invariably exhibit a well defined wall. Warthin's tumor can present areas of lesser density, and the metastatic lymph nodes can appear with necrotic or low-density zones, or even present variable wall thicknesses. In any case, intraglandular adenopathies are not usually found, and Warthin's tumor moreover does not usually present at submaxillary level. Most salivary lesions contain saliva, which in many cases is accessible to FNAB.

Lipomatous lesions in turn show a low radiological density, while tumors of neural origin tend to be more radiodense and contain necrotic zones (1).

As regards the pathogenesis of these lesions, two theories or mechanisms have been proposed to distinguish between mucoceles and mucous retention cysts. Partial obstruction of the salivary duct (due to inflammation, calculi or tumor growth), with subsequent duct dilatation (but not rupture) appears to give rise to a true salivary cyst, with epithelial lining of the cyst wall, also known as a retention cyst, sialocyst, etc. (1,2,10,11). By far most of these lesions (96%) affect the major salivary glands, and the patients are typically older than in the case of mucocele - though the two lesions are clinically indistinguishable (10).

In contrast, duct rupture (often caused by trauma or previous surgical interventions) directly produces extravasation or leakage of the mucous contents and infiltration of the surrounding soft tissues, with a secondary inflammatory response and the formation of granulation tissue. This gives rise to a pseudocyst lacking an epithelial lining, also referred to as a mucocele or mucous extravasation phenomenon (1,2,10,11).

A number of authors have attempted to clarify the pathogenesis of mucous retention cysts, relating them to spontaneous changes in the eosinophilic - oncocytic epithelium, or describing them as a cystic form of papillary cystoadenoma (12). Other authors consider oncocytic metaplasia in retention cysts to be the response to partial duct obstruction (13-15).

The case presented constitutes an unusual example of submaxillary mucocele. The diagnosis is mainly based on clinical and radiological evaluation of the lesion. In this sense, both CT and magnetic resonance imaging are able to define the location and possible origin of the lesion, facilitating the differential diagnosis with other pathologies such as ranula and/or cervical ranula. Orthopantomography and sialography usually offer little information, however. FNAB can identify the composition of the cyst contents, revealing the presence of abundant amylase and proteins such as mucin.

Numerous management options have been proposed for treating cervical mucoceles, including conservative approaches such as aspiration (with the risk of damaging important structures or relapse), the injection of sclerotizing agents, irradiation, marsupialization and drainage of the cyst cavity. On the other hand, the proposed surgical options comprise simple exeresis of the lesion and of the submaxillary gland, or even exeresis of the mucocele, submaxillary gland and sublingual gland adopting a transcervical approach or combining a transcervical and transoral approach.

Since 90% of all mucoceles are extravasation cysts lacking an epithelium, cyst exeresis is not obligate, and moreover may prove complicated or incomplete. Total removal of the gland originating the lesion is required, however, in order to prevent relapses.

In our opinion, in cases of submaxillary mucocele, it is necessary to resect the lesion and submaxillary gland, adopting a classical submaxillectomy approach. In the event the clinical or radiological findings indicate that the mucocele affects or is in intimate contact with the sublingual gland, the latter should also be removed in order to minimize the risk of relapse.

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