Cystic Neck Masses – A diagnostic and management challeng

Abstract

We discuss the case of a 41 year old gentleman referred to the one-stop clinic with a neck mass. An ultrasound scan and FNAC and subsequent excision biopsy showed a squamous lined cystic lymph node, with some focal positivity for cytoplasmic p16 staining. The pathology was potentially in keeping with a benign cystic lesion however a metastatic SCC could not be excluded.Cervical metastasis is often the only presenting feature in patients with squamous cell carcinoma of the head and neck (HNSCC) [1]. These metastatic foci frequently undergo cystic degeneration, and may be difficult to distinguish from other benign cystic lymphoepithelial lesions of the head and neck [2]. Cervical metastates from primaries in the oropharynx have been shown to be more likely to undergo these cystic changes in comparison to squamous cell carcinoma from other head and neck sites [3][4][5].During the investigative work up of these cases, fine needle aspiration for cytopathology (FNAC) may be performed. However, the results obtained are not always diagnostic. To increase the specificity of FNAC, immunohistochemistry for p16 is often performed, as p16 overexpression has been shown to act as a surrogate marker of Human Papilloma Virus (HPV) associated HNSCC [6] HPV, particularly subtype 16, has been shown to be a causative agent in a subset of HNSCC [7,8]. The majority of these HPV related carcinomas localise to the tonsil; which in turn is the most common site for primary tumour in the context of cystic metastasis [3,9]. Hence, previous studies have shown p16 positivity to thus correlate with oropharyngeal primary tumours [10].Nonetheless, the value of this marker in the differentiation between benign and malignant cystic lesions of the head and neck remains unclear. A case series by Pai et al showed that p16 staining was negative in all aspirates of branchial cleft cysts sampled (n = 4), and positive in 36% of the aspirates from malignant SCC cysts (n = 11) [11]. In contrast, a series reported by Cao et al also evaluating p16 staining in aspirates from cystic neck lesions, reported that up to 42% of benign lymphoepithelial lesions (n = 12) and 19% of malignant squamous lesions (n = 16) were positive for p16 [2]. Cervical metastasis is often the only presenting feature in patients with squamous cell carcinoma of the head and neck (HNSCC). These metastases frequently undergo cystic degeneration, and may be difficult to distinguish from other benign cystic squamous lesions of the head and neck. Fine needle aspiration for cytopathology (FNAC) is frequently performed, but the results obtained may not be conclusive. P16 immunohistochemistry may be carried out. However, the value of this test in differentiating between benign and malignant cystic lesions of the head and neck remains unclear. Cystic Neck Masses -A Diagnostic and Management ChallengeAbstract