Identification of a metastatic lung adenocarcinoma of the palate mucosa through genetic and histopathological analysis: a rare case report and literature review

Abstract

BackgroundCancers of unknown primary origin (CUPs) are reported to be the 3-4th most common causes of cancer death. Recent years have seen advances in mutational analysis and genomics profiling. These advances could improve accuracy of diagnosis of CUPs and might improve the prognosis of patients with CUPs.Case presentationA 76-year old male with an adenocarcinoma of unknown primary origin in the lung presented with another tumor of the palate mucosa. The tumor cells in the pleural effusion were all negative for immunohistochemical markers (TTF-1 and Napsin A) and lung-specific oncogenic driver alterations (EGFR mutation and ALK translocation). The tumor of the palate mucosa was likewise identified as an adenocarcinoma, and the cells showed cytological similarities with the tumor cells in the pleural effusion; TTF-1, Napsin A, EGFR mutation and ALK translocation were all negative. This result suggested that origins of the tumors of the palate mucosa and in the lung were the same, even though the origin had not yet been determined. Next, we addressed whether the tumor of the palate mucosa was a primary tumor or not. Secretory carcinoma (SC), which is a common type of minor salivary gland tumor (MSGT), was suspected; however, mammaglobin was negative and ETV6-NTRK3 (EN) fusion was not observed. Other MSGTs were excluded based on histological and immunohistochemical findings. Furthermore, an additional examination demonstrated an oncogenic KRAS mutation at codon 12 (p.G12D) in both palate tumor and in pleural effusion. KRAS mutation is known to exist in one-third of lung adenocarcinomas (LUADs), but quite rare in MSGTs. The possibility of metastasis from other organs was considered unlikely from the results of endoscopic and imaging studies. This result indicated that the primary site of the CUP was indeed the lung, and that the tumor of the palate mucosa was a metastasis of the LUAD.ConclusionsA tumor of the palate mucosa that showed diagnostic difficulties was determined to be a metastatic LUAD by genomic alterations and histopathological findings.Electronic supplementary materialThe online version of this article (10.1186/s12885-019-5277-1) contains supplementary material, which is available to authorized users.

Metastasis of pulmonary adenocarcinoma to the oral cavity: A case report and literatures review of the last 30 years

“…Several studies have recommended palliative treatment (e.g., surgical treatment, chemotherapy, and radiotherapy) to improve the quality of life (QOL) and to maintain the patient's comfort 7,8 . We found 54 cases of oral metastasis of PCs that were reported from 1991 to 2021 in PubMed and Google scholar 9–45 and reviewed these cases, including our case. Kaplan‐Meier survival analyses were performed to determine whether palliative treatment affected overall survival.…”

“…In our review, 41 of 54 patients received palliative treatments, and surgical treatments were common ( n = 10), followed by chemoradiotherapy ( n = 8) (Table 1). 8–44 There were no significant differences in the survival times between patients with and without palliative treatment at 6.49 and 4.36 months, according to the results of the Kaplan‐Meier test (log rank test: P = 0.437, Figure 4), which suggested that palliative treatment had no effect on survival time. Our patient was able to consume food orally using the upper denture after surgical treatment, showing that even if radical therapy cannot be administered, palliative treatment for maintaining oral function may contribute to the improvement of the QOL.…”

Metastatic Lung Cancer to the Head and Neck: A Clinico-Pathological Study on 21 Cases with Narrative Review of the Literature

“…Distant bone involvement in lung cancer cells generally manifests as osteolytic lesions, additionally in the jaw (mainly in the posterior mandible and mostly originating from adenocarcinoma). The gingiva is also reported to be frequently involved in metastases [ 2 , 3 , 4 , 5 , 6 , 7 , 39 , 40 , 41 ]. With regard to this, following the analysis of numerous studies in the literature, there is an evident need to distinguish lesions involving the gingiva or the bone (intraosseous) alone, from those involving both.…”