Non-sebaceous Lymphadenoma of the Thymus: a Case Report

Background: non-sebaceous lymphadenoma (NSL) is a rare benign tumor with a predominant lymphoid background within which is embedded solid or duct-like structures squamous epithelial nests, lacking of sebaceous differentiation. Non-sebaceous lymphadenoma most commonly arises within the salivary glands. However, Non-sebaceous lymphadenoma arises in the thymus have not been reported.Case presentation: A 53-year-old female patient, computed tomography (CT) scan of the chest for patient showed a nodular (19 ×13 × 16-mm) in the anterior mediastinum, and with mild homogeneous enhancement on contrast-enhanced CT. The patients underwent total thymectomy with removal of the anterior mediastinal nodule by thoracoscope via below the costal margin of the Xiphoid process. Microscopically, the tumor was composed of epithelial nests and prominent lymphoid stroma, with a capsule and clearly demarcated from the surrounding thymus tissue. The epithelial nests are arranged in solid nests or duct-like structures, lacking of sebaceous differentiation and cytological atypia. The pathological diagnosis was lymphadenoma, non-sebaceous type. There were no signs of recurrence 6 months after the surgery.Conclusions: There are very few reported cases of non-sebaceous lymphadenoma occurred in thymus in the medical literature. So accurate understanding of the histopathologic diagnosis of this rare tumor is important to avoid unnecessary overtreatment.

Literature Review of Sebaceous and Non-Sebaceous Lymphadenoma

Lymphadenoma of the salivary gland is a rare form of tumor that can be branched into Sebaceous Lymphadenoma (SLA) and Non-Sebaceous Lymphadenoma (NSLA). It is painless, hyperdense, shiny yellowish/brownish unicystic or multicystic mass which is encapsulated and well defined having lymphocytic and/or lymphoid follicles background present with or without sebaceous differentiation. Both SLA and NSLA are predominantly located in parotids with occasional case appearing in minor salivary glands and has <100 and <50 reported cases respectively in English literature. We have attempted to compile reported case studies on SLA and NSLA and tried to make analysis on the basis of findings. Our analysis revealed that both SLA and NSLA are often non-malignant in nature but feature of malignancy cannot be completely ruled out. Data also found that SLA and NSLA has a significant gender bias towards males but NSLA is more likely to appear at an early age as compared to SLA which often emerge after the 5th decade of life. Further, differential diagnosis should be considered to distinguish SLA and NSLA from Warthin’s tumor, pleomorphic adenoma, mucoepidermoid carcinoma, cystadenoma, lymphoepithelial cysts, myoepithelial sialadenitis, malignant lymphoma and metastatic adenocarcinoma of lymph node. This review discusses various techniques used in the past studies that can be helpful in making differential diagnosis.

Non-sebaceous Lymphadenoma of the Parotid Gland Mimicking a Pleomorphic Adenoma

Non-sebaceous lymphadenoma of the salivary glands is a rare benign lesion, first described in 1991. We present the case of a 54-year-old woman, with a right parotid mass. She underwent right superficial parotidectomy, and histopathology reported a non-sebaceous lymphadenoma due to an encapsulated lesion and multiple non-atypical epithelial inclusions without sebaceous differentiation. The etiology of non-sebaceous lymphadenoma is not yet understood, but it can arise predominantly from the parotid gland. Surgical excision is the treatment of choice.

Non-sebaceous lymphadenoma of the submandibular gland: diagnostic challenges in the head and neck cancer pathway

Non-sebaceous lymphadenoma (NSLA) is a rare benign salivary gland tumour with lymphoid and epithelial components and without sebaceous differentiation. The large majority of the reported cases arise within the parotid gland. We present an NSLA arising from the submandibular gland. The tumour presented as a painless longstanding neck lump. Ultrasound, fine needle aspiration, MRI and positron emission tomography found features supportive of squamous cell carcinoma. The patient was treated with surgery for oropharyngeal carcinoma of unknown origin, in accordance with local and national guidelines. The final histological assessment revealed the level Ib neck lesion to be NSLA. Although a rare occurrence, these lesions may pose a diagnostic challenge in the head and neck cancer pathway.