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

Background

Cancers 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 presentation

A 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.

Conclusions

A tumor of the palate mucosa that showed diagnostic difficulties was determined to be a metastatic LUAD by genomic alterations and histopathological findings.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5277-1) contains supplementary material, which is available to authorized users.

Diagnostic role of detecting HPV in a FNAC of metastatic laterocervical lymph node in a case of occult HPV-related head and neck squamous cell carcinoma

Human papillomavirus (HPV)-related head and neck squamous cell carcinomas (HNSCC) are radiosensitive tumors and have a better prognosis than the conventional keratinizing HNSCC. Despite extensive radiographic and clinical evaluation in approximately 3% to 5% of patients who present with cervical lymph node metastases, the primary tumor remains occult. The lack of a clinically identifiable primary tumor usually leads to more aggressive therapy, which can result in higher morbidity. Herein, we report a case of a patient with an occult HPV-related HNSCC, diagnosed detecting HPV in a fine needle aspiration cytology (FNAC) of metastatic laterocervical lymph nodes.

Is It Contralateral Axillary Metastasis or Occult Breast Cancer?: A Confusing Case Report

We report the case of a 43-year-old woman with primary left breast cancer presenting metastatic lymphadenopathy in the contralateral axilla. This patient represents a diagnostic and therapeutic challenge because primary breast cancer, occult contralateral breast cancer, and extra-mammary primary lesion can all be the source of the contralateral axillary metastasis. Left breast-conserving surgery, left sentinel lymph node biopsy, right breast mass excision, and right axillary lymph node dissection were performed. Immunohistochemical analysis revealed that the left breast cancer specimen was positive for estrogen receptor (ER) and progesterone receptor (PR), but negative for human epidermal growth factor receptor 2 (HER2). In contrast, the right axillary lymphadenopathy specimen was negative for ER and PR, but positive for HER2. Further investigation revealed no evidence of occult primary cancers or extra-mammary tumors. After surgical intervention, the patient was treated with adjuvant chemotherapy, adjuvant radiation therapy, and targeted therapy with trastuzumab. Two years after diagnosis, she is free of disease and presently being treated with tamoxifen.