Małgorzata Dębska-Rutkowska, Piotr Kwast, Monika Jabłońska-Jesionowska, *Lidia Zawadzka-Głos
Diagnostic difficulties in salivary gland tumors in children
Trudności diagnostyczne guzów dużych gruczołów ślinowych u dzieci
Department of Pediatric Otolaryngology, Medical University of Warsaw, Poland
Head of Department: Associate Professor Lidia Zawadzka-Głos, MD, PhD
Streszczenie
Wstęp. Guzy dużych gruczołów ślinowych, ze względu na rzadkość występowania oraz szerokie spektrum możliwych rozpoznań, stanowią wyzwanie dla lekarza. Badania obrazowe są kluczowym elementem procesu diagnostycznego, choć ich wyniki często nie dają możliwości postawienia ostatecznego rozpoznania.
Cel pracy. Celem pracy była ocena przydatności badań dodatkowych w diagnostyce guzów dużych gruczołów ślinowych u dzieci.
Materiał i metody. Dokonano analizy retrospektywnej danych medycznych dzieci ze zmianami guzowatymi ślinianki przyusznej lub podżuchwowej hospitalizowanych w Klinice Otolaryngologii Dziecięcej Warszawskiego Uniwersytetu Medycznego w latach 2012-2017.
Wyniki. U 8 dziewczynek i 7 chłopców w wieku od 4 miesięcy do 17 lat rozpoznano 6 guzów mieszanych, 3 naczyniaki krwionośne oraz po jednym przypadku naczyniaka limfatycznego, mięsaka prążkowanokomórkowego i raka śluzowo-naskórkowego. U wszystkich pacjentów wykonano badanie ultrasonograficzne (USG) ślinianek oraz tomografię komputerową (TK) i/lub rezonans magnetyczny (MRI) twarzoczaszki. Na podstawie USG rozpoznano większość (66%) guzów mieszanych. USG oraz TK lub MRI z kontrastem pozwoliły postawić rozpoznanie u wszystkich 4 pacjentów z naczyniakami. U 2 pacjentów na podstawie badania histopatologicznego rozpoznano nowotwór złośliwy ślinianki przyusznej.
Wnioski. Podstawowym badaniem diagnostycznym guzów dużych gruczołów ślinowych pozostaje USG, uzupełniane w razie konieczności o TK lub MRI. Badania obrazowe w niektórych przypadkach nie pozwalają na postawienie ostatecznej diagnozy. Rozpoznanie ostateczne guzów ślinianek (oprócz naczyniaków) ustala się na podstawie badania histopatologicznego. Najczęstszym guzem ślinianek u dzieci starszych jest guz mieszany, a u niemowląt – naczyniak. Należy pamiętać o możliwości wystąpienia u dzieci bardzo rzadkich guzów ślinianek, takich jak mięsak lub rak.
Summary
Introduction. Tumors of major salivary glands, due to their low incidence and the wide spectrum of possible diagnoses, are a challenge for physicians. Imaging studies are the key elements of the diagnostic process, although their results often do not provide a definitive diagnosis.
Aim. The aim of the study was to assess the usefulness of additional tests in the diagnosis of tumors of major salivary glands in children.
Material and Methods. A retrospective analysis of medical data of children with tumors of parotid or submandibular salivary gland hospitalized in the Department of Pediatric Otolaryngology of Medical University of Warsaw from the years 2012-2017 was performed.
Results. In 8 girls and 7 boys aged between 4 months and 17 years, the following diagnoses were established: 6 mixed tumors, 3 hemangiomas, 1 lymphangioma, 1 rhabdomyosarcoma, and 1 mucoepidermoid carcinoma. In all of the patients, ultrasound (US) of salivary gland, computed tomography (CT) and/or magnetic resonance imaging (MRI) of the head were performed. US examination enabled to diagnose the majority (66%) of mixed tumors. US and CT or MRI with contrast enabled to recognize angiomas in all 4 patients with this lesion. In 2 patients, malignant neoplasm was diagnosed based on the histological examination.
Conclusions. US remains the primary diagnostic test in patients with tumors of major salivary gland. When necessary, it can be supplemented with CT or MRI. In some cases, imaging studies do not enable to establish a definite diagnosis. The definite diagnosis of salivary gland tumors is established based on the results of the pathological examination (except for angiomas). The most common salivary gland tumor in older children is mixed tumor, and in infants – angioma. It must be remembered that very rare salivary gland tumors, such as sarcomas and carcinomas, may also occur in children.
Introduction
Salivary gland tumors are not common in pediatric patients (1-6). Only 3-5% of all salivary gland tumors occur at the developmental age (1, 7). Salivary gland tumors constitute 8% of pediatric head and neck tumors (8). All the histological types of salivary gland tumors that are reported in adult patients also occur in children, but their incidence is different (1, 5, 7). According to the World Health Organization (WHO) classification from 2005, almost 50 histological types of salivary gland tumors can be distinguished (9). Malignant salivary gland tumors occur relatively more often in children than in adults and are more common in younger children (4, 5). Malignant tumors occur more frequently in minor salivary glands, and tumors of major salivary glands are more likely to be benign (6).
In most of the studies, ca. 60-70% of salivary gland tumors are benign (1), although some studies report a 1:1 ratio of malignant to benign lesions (3, 10). The most common benign tumors include: pleomorphic adenoma, also known as mixed tumor (łac. adenoma pleomorphum, tumor mixtus), hemangioma, and lymphangioma. Mucous retention cysts, usually localized in minor salivary glands, are usually not included in the statistical analyses of salivary gland tumors, although they represent 2-5% of the findings in the parotid gland (11).
Aim
The aim of the study was to assess the usefulness of additional tests in the diagnosis of tumors of major salivary glands in children.
Material and Methods
Retrospective analysis of medical data of 15 children with tumors of parotid and submandibular salivary glands hospitalized in the Department of Pediatric Otolaryngology of Medical University of Warsaw in the years 2012-2017 was performed. Medical history of the patients, along with additional tests, including imaging studies, were analyzed.
Results
During 5 years between October 2012 and July 2017, 15 children with tumors of parotid and submandibular glands were hospitalized in the Department of Pediatric Otolaryngology, including 8 girls and 7 boys aged between 4 months and 17 years.
In most cases, salivary gland tumor was accidentally identified by the child’s physician or their parents. The time between the first identification of the tumor and the definite diagnosis varied from ca. 1 month (in case of hemangiomas) to a few years (in case of mixed tumors). The tumor was asymptomatic in 13 children, with no pain or facial nerve palsy. Two patients developed inflammation of the hemangioma. These children complained of pain, fever was also observed. Antibiotic treatment was required.
Tumor size varied from 15x18x11 mm to 37x34x24 mm. Palpatively, solid tumors were round, cohesive, hard. Hemangiomas that were currently not inflamed were soft, whereas inflamed hemangiomas were hard, with altered and warmed skin above the tumor.
All patients underwent basic blood tests (with no significant abnormal findings), ultrasound (US) of salivary gland and computed tomography (CT) and/or magnetic resonance imaging (MRI) of the head in case of diagnostic difficulties. The tumors were localized in parotid gland in 14 cases (7 on the right and 7 on the left) and in the right submandibular gland in 1 case.
Definite diagnoses included 6 cases of mixed tumors, 3 hemangiomas, 1 lymphangioma, 1 rhabdomyosarcoma, and 1 mucoepidermoid carcinoma. In 3 cases, pathological examination did not confirm the neoplastic nature of the lesion. These cases included 1 case of enlarged intraglandular lymph nodes, 1 case of fibrous tissue with necrosis and hemorrhages, and 1 case of non-specific inflammatory lesions.
In case of mixed tumor (6 patients: 4 girls and 2 boys aged between 11 and 17 years of age, mean age: 14.3 years), findings in ultrasound were described as solid, well demarcated, polycystic, although in 2 cases liquid content was found and cysts were suspected. In these patients, computed tomography was also performed, and it revealed a limited heterogenous tumor with low contrast gain. One patient underwent MRI. US examination enabled to diagnose the majority (66%) of mixed tumors. The patients were qualified for surgical treatment.
In patients with hemangiomas of salivary glands (3 girls aged 4 months, 7 months, and 7 years), ultrasound examination revealed a well-vascularized lesion or a lesion with visible blood flow, and in a patient with lymphangioma (12-year-old boy) – with no visible flow. The diagnostics was supplemented with CT or MRI with contrast, which demonstrated contrast enhancement in case of hemangiomas. These imaging studies enabled to establish diagnosis in all 4 patients. Biopsy of the lesions was not performed. Children with hemangiomas were treated conservatively – propranolol was used with good effect. The child with lymphangioma remains in the outpatient care, where the lesion is observed.
Two patients were diagnosed with malignant tumor of the parotid gland. In the case of a 6-year-old boy with rhabdomyosarcoma (lat. rhabdomyosarcoma embryonale), ultrasound examination revealed a well-vascularized solid polycyclic lesion measuring 20x18x14 mm. After 2 weeks, MRI examination revealed a mass in the superficial and deep lobe of parotid gland measuring 53x45x41 mm, reaching parapharyngeal space, modelling the lumen of nasopharynx, and compressing internal jugular vein. The invasion of neighboring structures was not observed. In the case of an 8-year-old boy with mucoepidermoid carcinoma (lat. carcinoma mucoepidermale), ultrasound examination revealed an oval, heterogenous, hypoechogenic tumor measuring 17x13x14 mm. Ultrasound-guided fine needle aspiration (FNA) was performed, and the results were identical with subsequent histopathological examination. No further imaging studies were performed. In both cases, the patients were qualified for surgical treatment, and then referred for further oncological treatment.
In 3 patients, neoplastic lesions were not confirmed. In a 2.5-year-old girl, enlarged lymph nodes were revealed in the ultrasound examination and therefore, no surgical treatment was offered. In another patient (12-year-old boy), ultrasound revealed a solid, well-defined lesion. Based on the US, a cyst with dense collection was suspected. In CT, a well-defined lymph node was described. Due to the discrepancies in the imaging studies, the patient was qualified for surgery. In the post-operative histopathological examination, fibrous tissue with necrosis and hemorrhages was described. It was suggested that the lesion may be of post-traumatic origin. In the last patient (15-year-old boy), ultrasound examination revealed a few solid, well-defined, spherical lesions morphologically similar to lymph nodes. In CT, a not well-defined, enhancing mass displacing the masticator muscle was revealed. This patient was also qualified for surgical treatment. The results of the histopathological examination described non-specific inflammatory lesions. Three months after that, lung tuberculosis was diagnosed in this patient.
In 5 children, fine needle aspiration biopsy (FNA) was performed: in 2 cases, mixed tumor was diagnosed, and in one case, mucoepidermoid carcinoma was observed. These findings were confirmed in the later histopathological examination of the tumors. In 2 cases (rhabdomyosarcoma and lymph node in the gland), FNA was non-diagnostic.
Ten children were enrolled for the surgical treatment (4 patients with angiomas and 1 patient with enlarged lymph nodes in the gland were not qualified for the surgery). Nine partial superficial parotidectomies and one submandibular salivary gland excision were performed. The peri- and postoperative course was, in all cases, uncomplicated.
Discussion
Bentz et al. in a study of 324 patients found that 60% of parotid tumors were hemangiomas, less than 30% – lymphangiomas, and only about 13% amounted for other tumors. 60% of the lesions were located in the parotid gland, while the submandibular gland and minor salivary glands were the location of 20% of tumors each. The most common non-vascular tumor in this material was pleomorphic adenoma (2). Hemangiomas, emerging shortly after birth and growing to one year of age, are usually subject to spontaneous involution at a later age (3). Due to their characteristic clinical course, they are usually diagnosed in infancy (3). It has been shown that the involution process is slower for salivary gland hemangiomas than for hemangiomas located in other organs (3). 80% of salivary gland hemangiomas are located in the parotid gland (3).
Craver et al. (7) analyzed a group of 213 children with salivary gland tumors. In 36 patients, neoplastic tumors were diagnosed, ca. 10% of which were malignant. The most common neoplasm was pleomorphic adenoma, and the second most frequent was lymphoma. Hemangioma was among the less common lesions (7). The small percentage of hemangiomas in this group of patients could be due to the fact that the researchers only analyzed the patients that had undergone surgery. Hemangiomas, easy to diagnose and treated conservatively, are generally not subject to histopathological examination because they are not operated (2).
The most common malignant neoplasms of salivary glands in children are: mucoepidermoid carcinoma (lat. carcinoma mucoepidermale), acinic cell carcinoma (lat. carcinoma acinocellulare), adenoid cystic carcinoma (lat. carcinoma adenoides cysticum), and rhabdomyosarcoma (lat. rhabdomyosarcoma) (1, 5). The first three types represent 80-90% of the cases of malignant salivary gland tumors in children (1).
In our material, the incidence of particular types of salivary tumors was consistent with the literature reports.
The diagnostic process for salivary gland tumors starts with a laryngological examination, including the two-handed examination (11). The majority of non-inflammatory lesions present themselves as an unpainful, growing, hard tumor (11). Both benign and malignant tumors are characterized by asymptomatic initial clinical course (4).
Ultrasound examination (US), computed tomography (CT), and magnetic resonance imaging (MRI) are used for imaging of salivary glands (1, 3). Vascular lesions are easily seen and recognised in US and this examination is usually sufficient to diagnose them (4). High resolution US is considered to be one of the best salivary gland imaging, as the superficial localization of the structures enables their thorough examination (12, 13). Ultrasound is primarily characterized by high sensitivity and a slightly lower specificity.
Computed tomography and magnetic resonance imaging are generally performed after the US in case of diagnostic doubt. They are also used for the assessment of the area of retromandibular fossa as well as deep parts of the soft tissues of the neck (1, 11). MRI, which is more specific than US, depicts soft tissues with a high accuracy, whereas CT is best suited for evaluating signs of bone destruction. The final diagnosis in case of solid tumors is based on the results of histopathological examination (4, 12).
Fine needle aspirational biopsy (FNA) is an examination that clinicians frequently use when qualifying for surgical treatment of salivary gland tumor, because it enables to distinguish malignant neoplastic tumor from an inflammatory lesion or a benign tumor with a high probability, and its sensitivity reaches 80-90% (14). However, FNA is not equivalent to the histopathological assessment of an excision or an entire lesion, and it should be evaluated only by experienced cytologists. Finally, in case of a strong suspicion of a neoplastic tumor, the patient should be qualified for surgery independently of the FNA results, and in doubtful cases, the result of FNA may help to decide on the necessity of surgery, but cannot be the basis for the final diagnosis (4, 14).
Commonly accepted methods of surgical treatment of benign salivary gland tumors include hemiparotidectomy of the superficial lobe of the parotid gland in case of tumors located laterally from the facial nerve branches and total parotidectomy in case of tumors located deeper in the gland. In case of malignant lesions, total parotidectomy is usually performed. Radiotherapy and chemotherapy are used in exceptional cases, generally complementary to the surgical treatment (1).
In our paper, we describe a case of an inflamed lymph node in the parenchyma of the parotid gland of a patient who was later diagnosed with lung tuberculosis. In spite of the lack of direct evidence of parotid tuberculosis, the clinical picture of a non-painful, enlarged tumor of the parotid gland may also correspond to this very rare diagnosis (16). Enlarged lymph nodes inside the salivary gland may be the only sign of the tuberculosis of this organ. Surgical excision of the affected lymph nodes is the most beneficial therapeutic options, although conservative antituberculous treatment is often effective as well (1).
Conclusions
US remains the primary diagnostic test in patients with tumors of major salivary gland. When necessary, it can be supplemented with CT or MRI.
In some cases, imaging studies do not enable to establish a definite diagnosis. The definite diagnosis of salivary gland tumors is established based on the results of histological examination (except for angiomas).
The most common salivary gland tumor in children is mixed tumor. It usually occurs in adolescents. In infants, the most common salivary gland tumor is angioma. It must be remembered that very rare salivary gland tumors, such as sarcoma and carcinoma, may also occur in children.
Piśmiennictwo
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