SARS-CoV-2 Detected in Tongue Squamous Cell Carcinoma Surgical Specimen

By Will Boggs MD

May 26, 2020

NEW YORK (Reuters Health) - SARS-CoV-2 was detected in formalin-fixed paraffin-embedded tissue specimens from a surgically resected tongue squamous-cell carcinoma of a patient who later developed COVID-19, according to a case report.

"We were able to detect viral RNA on formalin-fixed and paraffin-embedded tissue by RT-PCR using an assay originally developed for nasopharyngeal swabs," Dr. Massimo Barberis of the European Institute of Oncology, IRCCS, in Milan, Italy, told Reuters Health by email. "As far as we know, this was never before reported. These findings could offer new opportunities to study this infection on routine pathological samples."

Dr. Barberis and colleagues report the case of a 50-year-old man with tongue squamous-cell carcinoma who underwent surgical resection before the onset of COVID-19 symptoms and without knowing his SARS-CoV-2 status.

The entire specimen was fixed in 10% neutral buffered formalin for 24 hours before gross examination and sampling.

Two days after surgery the patient developed a fever, and laboratory tests revealed decreased lymphocytes. The next day he developed dry cough and mild dyspnea, and chest x-ray raised the suspicion of viral pneumonia. At that point, rapid SARS-CoV-2 testing performed on a nasopharyngeal swab yielded positive results. The patient gradually recovered after isolation and care in a dedicated COVID-19 department.

Slides of squamous-cell carcinoma, submandibular gland, and lymph nodes were selected for RNA extraction and SARS-CoV-2 testing. Viral RNA was detected in the carcinoma and in the histologically normal submandibular gland, but not in the lymph node specimens, the researchers report in the Journal of Clinical Pathology.

The authors were unable to demonstrate whether the virus is able to colonize neoplastic cells or which cell types in the salivary gland were infected. Nor could they quantify the tissue viral load or sequence the viral RNA.

"All surgical samples should be considered potentially infected and the personnel should be properly equipped with personal protection devices," Dr. Barberis said. "SARS-CoV-2 can be detected in morphologically normal salivary gland that may represent a potential viral reservoir. This observation raises the possibility of detecting the virus directly in saliva."

Dr. Xiankun (Kevin) Zeng of the United States Army Medical Research Institute of Infectious Diseases (USAMRIID), in Frederick, Maryland, who was not involved in the report, recently developed a dual-staining assay to detect SARS-CoV-2 antigen and RNA in formalin-fixed paraffin-embedded specimens. He told Reuters Health by email, "As far as I know, although the cellular entry receptor of SARS-CoV-2, ACE2, has been found expressed in the tongue squamous cells, this is the first proof of direct SARS-CoV-2 infection in tongue squamous cells."

"The tongue epithelium may be one of the targets or reservoirs of SARS-CoV-2 infection in the oral cavity," he said. "We should avoid touching our mouths (including tongues) with our hands to prevent infection."

"Further study is needed to see if tongue infection of SARS-CoV-2 also occurs in people without tongue squamous-cell carcinoma," Dr. Zeng said.

He added, "Proper handling of surgical samples is needed due to possible SARS-CoV-2 infection in patients without symptoms."

SOURCE: Journal of Clinical Pathology, online May 4, 2020