cystic squamous cell carcinoma metastasis

The majority of metastatic cervical lymph nodes in head-and-neck squamous cell carcinomas (HNSCCs) are solid masses. However, between 33% and 62% of cases are cystic metastatic squamous cell carcinomas (SCC).

Most cases of cystic squamous cell carcinoma (SCC) metastases in the upper neck are associated with an oropharyngeal primary, namely human papillomavirus (HPV)-associated SCC arising in the palatine or lingual tonsil.

Cystic SCC lymph node metastases of the head and neck region are strongly associated with the occult primary localized in the oropharynx.

The oropharyngeal origin should always be corroborated by p16 immunohistochemistry and HPV-specific testing because SCC arising in other sites, such as nasopharynx, skin or lungs may manifest with cystic neck metastases as well.

Addition of EBV testing in p16/HPV-negative cases can disclose the nasopharyngeal origin of the cystic neck metastases in a subset of cases.

Differential diagnosis

The most-common variety of solitary cervical cystic lesion is the branchial cleft cyst (BCC), which can become malignant.

According to the strict diagnostic criteria for branchial cleft cystic carcinoma (BCCC), proposed by Martin et al. [6] and modified by Khafif et al., fewer than 40 cases have been reported.

The majority of previously suspected BCCCs were actually metastatic cystic lymph nodes; misdiagnosis can occur due to the absence of long-term follow-up.

Thus, solitary metastatic cystic lymph nodes, from carcinomas of the upper aerodigestive tract, are difficult to differentiate from BCCCs, especially in patients more than 40 years of age.

The proportion of metastatic cystic SCCs initially diagnosed as BCCs, or BCCCs, ranges between 11% and 21%.

Metastatic cystic SCCs in the upper lateral neck are easily mistaken for BCCCs if the primary site of the carcinoma is not detected.

The majority of metastatic cervical lymph nodes in head-and-neck squamous cell carcinomas (HNSCCs) are solid masses. However, between 33% and 62% of cases are cystic metastatic squamous cell carcinomas (SCC).

Diagnosis and management for both clinicians and pathologists is problematic if lesions are characterized by a solitary cystic appearance.

The challenge, therefore, is to distinguish BCCC from occult metastatic cystic SCC, and to identify the primary site of metastatic cystic SCC in the head and neck.

See also

 solitary cervical cystic anomalies

Open references

 Human papillomavirus and cystic node metastasis in oropharyngeal cancer and cancer of unknown primary origin. Yasui T, Morii E, Yamamoto Y, Yoshii T, Takenaka Y, Nakahara S, Todo T, Inohara H. PLoS One. 2014 Apr 21;9(4):e95364. doi : 10.1371/journal.pone.0095364 PMID: 24752007 (Free)

 p16(INK4A) immunohistochemical staining may be helpful in distinguishing branchial cleft cysts from cystic squamous cell carcinomas originating in the oropharynx. Pai RK, Erickson J, Pourmand N, Kong CS. Cancer. 2009 Apr 25;117(2):108-19. doi : 10.1002/cncy.20001
PMID: 19365840 (Free)

References

 Origin of cystic squamous cell carcinoma metastases in head and neck lymph nodes: Addition of EBV testing improves diagnostic accuracy. Švajdler M Jr, Kašpírková J, Hadravský L, Laco J, Dubinský P, Straka Ľ, Ondič O, Michal M, Skálová A. Pathol Res Pract. 2016 Mar 14. doi : 10.1016/j.prp.2016.03.002 PMID: 27013059

 Case report of a p16INK4A-positive branchial cleft cyst. McLean T, Iseli C, Amott D, Taylor M. J Laryngol Otol. 2015 Jun;129(6):611-3. doi : 10.1017/S0022215114003223 PMID: 26004639