Presentation of cervical metastases and pathological mandibular fracture due to pulmonal adenocarcinoma: A case report.

Highlights • Oral metastatic tumors due to malignancies at distant locations are very rare.• Cervical metastases of level I and II due to adenocarcinoma of the lung have hardly been described before.• Diagnosis of unclear oral lesions requires extensive staging.• In cases of oligometastases in the oral region tumor resection may be a curative treatment.


Introduction
Metastases in the oral cavity represent approximately 1% of all oral malignancies [1,2]. With a mean survival time of 7 months after diagnosis, the prognosis is poor [3]. While in men lung cancer is one of the most common primary origin, in women, most known metastases originate from the breast [4]. Other locations include kidney, liver, prostate and colorectal cancers [3,4]. In general, jawbones are more likely to be affected than oral soft tissue [3]. Especially in adenocarcinomas of the lung, cervical lymph node metastases mostly present in the supraclavicular level. Although involvement of level I and II cervical lymph nodes has been reported before [5] their infiltration is extremely rare and already classified as M1 in the TNM classification [6].
In this report, we describe the case of pulmonal adenocarcinoma metastases to the mandible bone and cervical lymph node (level I and II) as the first sign of a metastatic tumor. The patient was referred to our department of oral and maxillofacial surgery by his dentist. This work has been reported in line with the SCARE criteria [7].

Presentation of case
A 50-year-old male was referred to the emergency department by his dentist with a perimandibular swelling. In the physical examination there was an indolent, fluid-filled swelling intraorally in the left mandible region with signs of infection. In his medical history an adenocarcinoma of the lung (pT3 pN2b L1 V1 Pn1 R1 M0) was treated operatively with the resection of the right superior lobe and radiotherapy 16 months ago. The patient is a former smoker, not taking regular medication. The common radiological diagnostics, including computed tomography (CT), showed a mandible fracture (Fig. 1) and abnormal perimandibular soft tissue as well as accentuated cervical lymph nodes (level IIa, left). Immunohistochemical analyses of a subsequent intraoral biopsy of the mandible identified a metastasis of the primary adenocarcinoma of the lung (strong expression of cytokeratin 7 (CK7) and thyroid transcription factor 1 (TTF-1)). Using a positron emission   tomography-computed tomography (PET-CT) further peripheral metastases could be excluded (Fig. 2). The interdisciplinary tumor board recommended a tumor resection and neck dissection. After a left hemimandibulectomy and left sided-selective functional neck dissection (level I-III) a CAD/CAM microvascular fibula transplant was used for reconstruction. The postoperative histopathological analysis revealed lymph node metastases in levels Ia, Ib and IIa. Postoperatively, the patient received adjuvant chemotherapy with carboplatin and pemetrexed.

Discussion
Dentists and surgeons are often confronted with unspecific symptoms like swelling, paresthesia, bleeding or tooth mobility [1][2][3][4]. The attention of a diligent dentist initiated further diagnostic steps in this case.
Here, metachronous oligometastases of the primary adenocarcinoma of the lung were histologically and immunohistochemically identified in the mandible as well as cervical lymph nodes. One has to distinguish between oligometastastic and polymetastatic disease, understanding oligometastases as a state where local cancer treatment can still be curative [8]. The definition of oligometastases is not clearly defined in literature. With up to 5 extrapulmonary metastases, the term describes an intermediate, potentially curable state between local disease and a progressed, metastatic disease [9]. While overall survival of metastatic non-small cell lung cancer (NSCLC) at the time of diagnosis is only 6 months, patients with oligometastases may have a better outcome due to surgical treatment [10]. Patrini et al. further identified the number of metastases and timing as additionally relevant factors in oligometastatic NSCLCs. Overall survival was lower in patients with synchronous lesions than with metachronous lesions [10]. Bone metastases had very limited survival rates compared to other extrathoracic organ sites, such as soft tissue or brain [9].
In this case, mediastinal lymph node involvement or other peripheral metastases could be excluded. The isolated cervical lymph node metastases of level I and II and the pathological mandibular fracture may be classified as extrathoracic metachronous oligometastases [6]. To the authors' knowledge, prior to this, only one case [5] has described level I and II lymph node metastasis following an adenocarcinoma of the lung. The combination with a pathological mandibular fracture is unique. Clearly, metastasectomy is controversial since overall survival is dependent on multiple factors and an operation might sometimes only prolong palliation. However, there are multiple cases where metastasectomy showed a higher survival rate [11]. In this case the absence of other peripheral metastases and the possibility of a surgical metastasectomy led us to the conclusion, that an operation to cure the patient could be performed.

Conclusion
Besides the rare occurrence of mandible metastases, this case proves that simultaneous cervical metastases are also possible. In cases with primary malignancies at a non-oral distant location, dentists and surgeons have to give special attention to the incidence of possible metastases of these malignancies.

Declaration of Competing Interest
The authors have no conflicts of interest.

Funding
There was no funding of the research.

Ethical approval
No ethical approval needed.

Consent
Written consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Author contribution
CS: Data collection, writing manuscript. CD: patient's surgeon, data collection. JOV: patient's surgeon, data collection, case discussion. NT: radiological assessment, visualization, recommendation in tumor conference, proof reading.
RW: patient's surgeon, recommendation in tumor conference, proof reading manuscript, visualization.

Registration of research studies
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Provenance and peer review
Not commissioned, externally peer-reviewed.