Sialometaplasia arising in the ectopic salivary gland ductal inclusions of multiple intraparotid lymph nodes

Abstract

Sialometaplasia, squamous metaplasia of salivary gland lobules, is a benign condition occasionally presenting with lesions clinically simulating malignancy. ''Necrotising sialometaplasia'', recognised by lobular infarction, necrosis, and simultaneous squamous metaplasia of ducts and acini is a well known condition. There are only a few reports of the ''proliferative type of sialometaplasia'', which is recognised by a more mature morphology of larger and more irregular metaplastic nests, lacking necrosis. This report describes a unique case of ''proliferative sialometaplasia of multiple intraparotid lymph nodes'' occurring in a 55 year old woman, presenting with multiple parotid lumps. This interesting case points to the importance of intraparotid lymph nodes as sites for multiple lesions of the parotid region. S ialometaplasia, squamous metaplasia (SM) of salivary gland lobules, is a benign condition occasionally presenting with lesions mimicking malignancy. Since the description of the necrotising type, 1 many cases have been published. The proliferative form has only been reported in a few cases in intraparotid lymph nodes (LNs).2 3 This type of sialometaplasia is recognised by solid squamous metaplastic nests involving ductal structures and lacking atypia and necrosis. CASE REPORTA 55 year old woman presented with left infra-auricular multiple lumps, of two years duration. She had undergone stapedectomy of the right ear five years previously.The patient had a 1.5 6 1.5 cm, non-tender, semimobile mass in the left preauricular region, and a similar mass in the tail of the left parotid gland. The functions of the facial nerve were bilaterally normal and the examination of the other head and neck sites including the other salivary glands was unremarkable. She had no complaints of xerostomia. Sonography revealed hypoechoic parotid nodules. The lesions were hyperdense with contrast enhancement on computed tomography scans. Magnetic resonance imaging demonstrated two spherical discrete masses. Lesions were hypointense on the T1 images and isointense on the T2 images with contrast enhancement (fig 1). The radiological conclusion was consistent with a benign tumour, in particularly pleomorphic adenoma, and the clinical diagnosis was that of pleomorphic adenoma and associated lympadenomegaly of intraparotid LNs. The routine laboratory examinations were not remarkable: white blood cell count, 8.1 610 9 /litre; haemoglobin, 135 g/litre; haematocrit, 39.3%; erythrocyte sedimentation rate, 21 mm/hour; antinuclear antibodies, antineutrophil cytoplasmic antibodies, human immunodeficiency virus were negative.Left superficial parotidectomy with preservation of the facial nerve was performed. Pathological examinationSuperficial parotidectomy revealed two encapsulated, 1.5 cm, grey/white nodules located at the poles. Histology showed that they were both LNs and six additional LNs were also identified. Five LNs revealed ductal salivary gland inclusions, almost totally replaced by SM, but retaining the lobular architecture of duct...

Necrotizing sialometaplasia versus invasive carcinoma of the head and neck: the use of myoepithelial markers and keratin subtypes as an adjunct to diagnosis

“…In the latter study, Furuse concluded that calponin and SMA were the most consistent markers of myoepithelial cells in pleomorphic adenomas. In one case of sialometaplasia that occurred in salivary nodal inclusions, SMA and S100 staining at the periphery of the metaplastic lobules was noted, 15 but apart from this, myoepithelial markers have not previously been examined in NSM or its related lesions.…”

“…Although necrosis is a defining feature in the description by Abrams, 5 most authors accept that it is likely to occur in the earliest stages and therefore may not always be seen by the time the patient comes to biopsy 1,12 . The lesion described as proliferative sialometaplasia shares many histological features with NSM, although in a distinct anatomical setting 15,16 …”

“…1,12 The lesion described as proliferative sialometaplasia shares many histological features with NSM, although in a distinct anatomical setting. 15,16 The importance of this lesion lies in the fact that it can be confused with SCC or MEC, both clinically and histologically, with the possibility of unnecessarily radical surgery. 1,14 The distinction is made histologically, with emphasis on the lobular morphology, bland appearance of the squamous islands and evidence of residual ductal lumina in these islands.…”

Adenoidzystisches Karzinom im heterotopen Speicheldrüsengewebe der zervikalen Lymphknoten

“…Sie führen durch ihre tumoröse Veränderung zu Symptomen und werden dadurch klinisch auffällig. Lymphoepitheliale Zysten, benigne lymphoepitheliale Läsionen sowie Sialometaplasien wurden im Bereich des intranodalen heterotopen Speicheldrüsengewebes beschrieben [6]. Bei der überwiegenden Mehrheit dieser heterotopen Speicheldrüsenläsionen handelt es sich jedoch um benigne Speicheldrüsentumoren, wobei das Zystadenolymphom (Warthin-Tumor) der Glandula parotis die häufigste Tumorentität darstellt [7].…”