Case report

An 82-year-old man was referred to the authors’ department for evaluation of a right-sided parotid mass. The history revealed a right-sided asymptomatic infrauricular mass of several years evolution (less than 5 years). Physical examination revealed an ill-defined mass, of maximum diameter 6 cm, in the right parotid region. The patient complained of mild paresia of the marginal branch of the facial nerve of several years duration ( Fig. 1 ). A more meticulous physical examination showed an almost imperceptible cutaneous scar in the right parotid region and right alveolar nerve hypoestesia. The patient did not remember when these neurological signs had appeared. A panoramic radiograph ( Fig. 2 ) showed multilocular, ill-defined osteolytic areas, which involved the entire right mandibular ascending ramus and body, reaching the canine region. With the presumptive diagnoses of a benign parotid gland tumour, a large mandibular odontogenic cyst or a large and aggressive odontogenic mandibular tumour, a cervicofacial computed tomography (CT) scan was performed.

An 82-year-old man with an ill-defined mass in the right parotid region and an almost imperceptible cutaneous scar in the right parotid region.

Panoramic radiograph showing an ill-defined area of osteolysis in the right mandibular ascending ramus and body, reaching the canine region.

Although many of the radiographic sections appeared to be affected by dental fillings and multiple shrapnel lodged in the neck, a large mass could be distinguished on the right parotid region with a hypodense centre and a hyperdense periphery that did not change with contrast ( Fig. 3 ). The patient reported a wound caused by shrapnel in the Spanish Civil War in 1936. FNA of the mass was performed resulting in 0.5 cc of blood and fatty material that did not yield diagnostic material. An initial differential diagnosis of parotid gland tumour was considered.

CT affected by dental fillings and multiple shrapnel lodged in the neck. A large mass could be distinguished on the right parotid region with a hypodense centre and a hyperdense periphery that did not change with contrast.

The patient underwent parotidectomy under general anaesthesia. The mass extended to the whole mandible, eroding both corticals in the middle portion of the ramus. Complete extirpation of the mass and a superficial parotidectomy was carried out preserving the orbicularis and frontal branches of the facial nerve and the mandibular defect was curretted. The inferior pole of the parotid gland was occupied by a greenish mass adhering to the adjacent parotid tissue with a 2.5 cm × 2 cm metallic fragment of shrapnel inside ( Fig. 4 ). Neither clinical nor histological signs of infection were found after removing the intraparotid mass. The cultures did not provide relevant information. The postoperative follow-up period was uneventful and the patient was discharged from hospital after 2 days. The long-term soft tissue and bone healing was uneventful.

Fragment of shrapnel (2.5 cm × 2 cm) lodged inside the parotid mass after parotidectomy. Other satellite fragments of shrapnel were seen in the histological examination ( Fig. 5 ).

Histological examination showed a foreign body reaction caused by shrapnel, revealing extensive fibrosis, chronic inflammation, and non-necrotizing granulomas. As well as the large fragment, other much smaller satellites fragments of shrapnel were seen during the histological examination ( Fig. 5 ).

Reaction to foreign body caused by shrapnel (200× magnification; haematoxylin and eosin staining).

Discussion

This case is unusual owing to its rare clinical presentation, the time between the injury and the symptoms appearing (63 years), the almost invisible scar at the point of entrance, the mandibular osteolysis (as seen on the panoramic radiograph) and the rapidly progressive growth in the last few months. These clinical findings suggested diagnoses of a parotid tumour, an odontogenic tumour or an odontogenic cyst.

The first interesting point of this case is the differential diagnosis of an apparent mass in the parotid region eroding the mandibular ramus suggesting a parotid tumour, an odontogenic tumour or a large mandibular cyst (like an odontogenic keratocyst) with soft tissue extension. The second interesting point is the exceptional clinical evolution of the wound. Clinical examination revealed a mass extending from the preauricular region to the angle of the mandible of several years duration in an 82-year-old man. The marginal nerve was slightly affected, and no skin changes or lymphadenopathy were noted. These clinical findings indicated a benign process. Eighty percent of parotid gland tumours are benign.

A benign neoplasm of the parotid gland was first suspected and FNA and CT were carried out. The diagnostic and therapeutic protocol for parotid tumours is well established, especially in benign neoplasms . Diagnosis is based on FNA cytology and radiology to locate the tumour mass .

FNA cytology is a valuable adjunct to preoperative assessment of parotid masses and may help to prepare the surgeon and patient for the appropriate surgical procedure. In this case it was not diagnostic. The parotid gland is unique in the number, diversity, and peculiarity of its pathological processes. This complexity has prompted discussion regarding the application of FNA cytology to parotid masses, primarily focusing on the reliability of FNA cytology as a diagnostic tool in guiding patient management , as reported in this case. Recent studies have confirmed a wide range of accuracy rates for FNA cytology evaluation of parotid masses, varying from 79% to 97% . These data cannot be uniformly anticipated across all diagnostic scenarios . FNA cytology is useful in avoiding surgery (inflammatory lesions) or limiting surgical procedures (benign tumours) . When planning the extent of surgery of malignant parotid tumours, the histological subtype and/or grade should be determined, so a histological diagnosis by frozen section analysis is required . Reliance on FNA cytology findings at the expense of clinical, radiographic, and intraoperative findings is unwarranted.

Regardless of whether FNA cytology is used routinely or selectively in patients with parotid masses, the findings should contribute to, and not replace, the overall diagnostic impression . CT scans with intravenous contrast show a well-circumscribed, hypodense, nonenhancing mass in the right parotid gland ( Fig. 3 ). This study was affected by multiple dental fillings and multiple shrapnel lodged in the neck. The radiological finding of a metallic fragment would suggest a traumatic antecedent in such a singular case, but no shrapnel was found in the parotid gland in the CT scan. Neither FNA cytology nor radiology was helpful in reaching an accurate and precise diagnosis before considering surgical treatment.

Foreign bodies lodged in the salivary glands are uncommon . Cases have been reported of wooden toothpicks, blades of grass, toothbrush bristle, fish bone, hair, nidus of lepthotrix, a piece of straw or grass, brome grass, stem or seed, portion of fingernail, spike or wheat, splinter of wood, thorn and chicken pinfeather and a piece of a ballpoint pen . Most of the reported foreign bodies lodged in the salivary glands reached the gland through Stenson’s duct or Wharton’s duct . Usually these foreign bodies are localized in glandular ducts and induce salivary calculus, recurrent sialadenitis or glandular sinus and cutaneous fistula Recurrent trismus and salivary calculus were also reported . The diagnosis of a foreign body in the parotid gland may be suspected when the injury is recent and symptoms such as infection, fistula or trismus are present . If the foreign body is radiopaque, the diagnosis may not be difficult. Any suspicion of a residual foreign body after penetrating parotid gland trauma can be clarified with a detailed radiological examination, which may provide further guidance for treatment . If it remains asymptomatic after the initial treatment (as in this case), the suspected diagnosis is very unlikely. R aspall & G onzalez reported an intraparotid foreign body, identified as a piece of ballpoint pen, the presentation of which mimicked a benign tumour. The treatment for parotid foreign bodies is early surgical exploration, and in delayed cases such as this, superficial parotidectomy may be needed .

Low velocity gunshot injuries (velocity up to 1000 m/s) to the parotid gland are well documented by authors such as Y ih et al. and M ajid . Reports of bullets lodged in the parotid gland caused by gunshot have been published and the effect of bullet injuries on the glandular tissue was discussed by K halil . K halil , in a study of 18 civilian maxillofacial wounds caused by firearms, reported a case in which the bullet remained lodged in the parotid gland. Recently, M ajid reported 16 patients with gunshot injuries to the cheek, 10 of whom had damage to the parotid. All injuries were high velocity gunshot injuries. M ajid classified the parotid gunshot wounds into three clinical types, depending on the location of the entrance and exit wounds and the severity of tissue lost. M ektubjian pointed out that, unlike high velocity gunshot injuries, low velocity gunshot injuries are associated with limited tissue destruction and exploration of the bullet tract through the tissues is not mandatory. If subsequent infection occurs, removal of the bullet is necessary. M ektubjian noted that the bullet was probably sterile, and the infection associated with gunshot wounds is usually due to clothing, wadding or other organic debris contaminating the wound . Metals (like shrapnel) may give rise to chemical and secondary bacterial inflammation of the surrounding tissue resulting in abscess or salivary fistula, and the salivary gland is the most responsible lesion due to autolysis by amylase . Clinical or histological signs of infection were found after removing the intraparotid mass.

When the traumatic incident is recent, exploration usually reveals other maxillofacial lesions and the radiological diagnosis confirms the position of the bullet. In these cases, usually produced by low energy gunshot injuries, the bullet destroys scarce tissue and some authors suggest not removing the foreign body when there are no symptoms . Despite this, complete removal of the foreign body penetrating the parotid gland is the procedure of choice for most authors, to avoid sialoadenitis, salivary fistula or other late complications, whether the foreign body is assumed to be harmful to the tissue or not .