A contrast-enhanced neck CT scan demonstrated a roughly 3 cm well-circumscribed, heterogeneously enhancing soft tissue mass on the right oropharyngeal posterior wall (Fig. 1B, yellow circle). No suspicious cervical lymph nodes were noted. Incidentally, the neck CT also detected a lesion in the left upper lobe of the lung. Subsequent dedicated chest CT revealed a multi-lobulated left upper lobe mass (~5.9 cm overall, with a 2.8 cm solid component) accompanied by peripheral ground-glass opacity (Fig. 1B, red arrow). This was highly suggestive of a primary lung malignancy. No other distant metastases were identified on imaging.

An incisional biopsy of the oropharyngeal mass was initially non-diagnostic, showing an atypical proliferation of mononuclear and multinucleated giant cells with a prominent histiocytic background but no definitive carcinoma cells. Given the unusual pathology, a repeat excisional biopsy of the PPW lesion was performed. Concurrently, a CT-guided needle biopsy of the left upper lobe lung mass was obtained. Histopathological analysis confirmed that both lesions were malignant and appeared histologically similar. The lung mass was identified as a pleomorphic carcinoma (sarcomatoid carcinoma), a rare subtype of NSCLC, containing spindle and giant cell components. The PPW lesion was confirmed as metastatic pleomorphic carcinoma. Immunohistochemistry of the PPW tumor showed focal nuclear positivity for TTF-1 and cytokeratin (CK7), consistent with a metastatic lung origin, while markers for lymphoma or melanoma were negative. No evidence of squamous dysplasia or carcinoma in situ was seen in the surrounding mucosa. These findings established that the oropharyngeal tumor was a distant metastasis from the primary lung carcinoma rather than a new primary head-neck cancer.

The case was discussed in a multidisciplinary tumor board. Given the synchronous presentation of a resectable primary lung tumor and a solitary oropharyngeal metastasis, an oligometastatic treatment approach was pursued. The lung lesion was addressed first with stereotactic body radiotherapy (SBRT) to maximize local control of the primary tumor while avoiding the morbidity of immediate lung surgery. The patient received SBRT to the left upper lobe mass at a dose of 60 Gy in 4 fractions over one week. This regimen was chosen for its curative intent in early-stage NSCLC. No systemic chemotherapy was administered.

Follow-up imaging six weeks after SBRT showed a robust response in the lung and a partial response in the oropharynx. The treated lung mass dramatically decreased from 26 mm to 11 mm in maximum diameter, with resolution of the associated ground-glass opacity. The PPW metastasis also shrank from ~3 cm to ~1.7 cm (Fig. 1C). Despite this partial regression, residual tumor persisted in the oropharynx. Because a complete response of the metastasis was not achieved, the decision was made to proceed with surgical resection of the oropharyngeal lesion for definitive local control.

Approximately three months after SBRT, the patient underwent TORS for removal of the remaining PPW tumor. Under general anesthesia with nasotracheal intubation, he was positioned supine in the Rose position (head extended and mouth opened widely as for tonsil surgery). A Feyh- Kastenbauer (FK) retractor was utilized to expose the oropharynx, retracting the tongue and soft palate to provide a direct line of sight to the posterior pharyngeal wall. The da Vinci Xi surgical system was docked with a three-arm setup: a 30° dual-lens endoscope was positioned through the central port, and two robotic instrument arms (a Maryland bipolar forceps and a monopolar spatula cautery) were used for tissue manipulation and cutting. The remnant oropharyngeal tumor, which appeared as an isolated nodular mass on the right PPW, was clearly identified endoscopically (Fig. 1D, left). Circumferential surgical margins were delineated approximately 5 mm around the lesion using electrocautery. With careful counter-traction and robotic instrument control, the tumor was excised en bloc, including the full thickness of the pharyngeal wall down to the prevertebral fascia to ensure an oncologic deep margin. The resected specimen measured roughly 3.0 × 2.0 × 1.5 cm (7 g). The tumor itself was ~2.0 × 1.8 cm, consistent with the post-SBRT imaging size. There was minimal bleeding; hemostasis was achieved with bipolar cautery and packing. No neck incision was needed. The robotic resection spared surrounding structures, and notably no tracheostomy or feeding tube was required. Intraoperative frozen section analysis was performed on the basal (deep) margin as well as the superior, inferior, medial, and lateral mucosal margins; all were reported as negative for tumor. The patient was extubated in the operating room and transferred to recovery without issue.

Permanent histopathology of the TORS resection confirmed a poorly differentiated pleomorphic carcinoma consistent with metastatic sarcomatoid carcinoma from the lung. The tumor demonstrated spindle and giant cell morphology with associated dense histiocytic inflammation (tumor-associated macrophage infiltrates), a pattern which likely contributed to the unusual initial biopsy appearance. There was no in situ carcinoma or dysplasia in the overlying mucosa. Lymphovascular invasion was present within the oropharyngeal tumor. All surgical margins were clear of malignancy on permanent sections (the closest margin was the lateral mucosal margin, approximately 4 mm from the tumor, and the deep margin at the prevertebral fascia was >1 mm clear). Immunohistochemical staining of the resected tumor showed focal positivity for TTF-1 in the nuclei of some tumor cells, diffuse positivity for cytokeratins (AE1/AE3, CK7), and a high proliferation index by Ki-67 (about 60% in hot spot areas). Markers for epithelial origin (EMA) were positive, while markers for melanocytic or hematologic lesions (S-100, CD68, CD45/LCA, etc.) were negative. EBV-encoded RNA in situ hybridization was negative, arguing against an Epstein-Barr virus-related nasopharyngeal carcinoma. These findings confirmed the diagnosis of metastatic pleomorphic carcinoma of lung origin and showed that the tumor retained some pulmonary immunophenotypic markers (TTF-1) even after radiotherapy.

The patient’s recovery from TORS was quick and without complication. He started a liquid diet on postoperative day 5 due to satisfactory early mucosal healing (Fig. 1D, right), and progressed to a soft diet without aspiration or significant odynophagia. He was discharged on postoperative day 9 in stable condition. Follow-up endoscopy at that time showed a clean operative bed with continued epithelialization and no residual tumor. Fig. 1 summarizes the timeline from initial presentation through SBRT and TORS, including key endoscopic and radiologic findings (panels A-D). The patient was subsequently monitored with regular surveillance. Given the rarity of his presentation, close follow-up was arranged with interval endoscopic examinations and imaging. At 10 months after the TORS resection, the patient remained asymptomatic and the oropharyngeal exam was normal; however, a surveillance neck CT revealed a new 0.9 cm enhancing lymph node at right level IIa (Fig. 2). This finding raised concern for a delayed regional metastasis, since no nodal disease had been evident previously. There were still no signs of recurrence at the PPW primary site (the surgical bed appeared normal on imaging and endoscopy), and no other distant lesions were found on systemic workup (chest imaging showed no progression in the treated lung). A fine-needle aspiration of the new neck node was positive for carcinoma, confirming regional nodal metastasis of the previously treated cancer.

The patient was offered curative-intent neck dissection for salvage. In July 2018 (approximately one year after TORS), he underwent a right modified radical neck dissection (mRND, type III), removing levels I-V lymph nodes while preserving the spinal accessory nerve, internal jugular vein, and sternocleidomastoid muscle. The surgery included removal of fibrofatty tissue in level IIa where the metastatic node was located. Additionally, given the concern for any occult primary in the oropharynx, bilateral tonsillectomies were performed during the same operation (even though the primary tonsils had appeared normal, to conclusively rule out an unrecognized primary tonsillar carcinoma). The neck dissection procedure was completed without significant complications, aside from a minor tear in the right internal jugular vein which was repaired intraoperatively. The patient had an uneventful postoperative course with standard wound care and physical therapy for shoulder rehabilitation.

Histopathological analysis of the neck dissection specimen identified metastatic carcinoma in 2 out of 10 lymph nodes dissected from level IIa (right upper jugulodigastric region). The largest metastatic focus measured 1.8 cm. There was no extracapsular extension of tumor noted, indicating the disease was confined within the lymph node capsules. All other dissected nodes from levels I, IIb, III, IV, and V were negative for malignancy. The bilateral tonsils removed during surgery showed only reactive lymphoid hyperplasia with no evidence of tumor in either tonsil. The metastatic carcinoma in the positive nodes was morphologically consistent with a poorly differentiated carcinoma. Given the patient’s history, immunohistochemical studies were performed on the nodal tumor: the cells were negative for TTF-1 and continued to be negative for high-risk HPV (by RNA in situ hybridization). These findings, combined with the prior history of a TTF-1-positive lung tumor and the absence of any other primary, supported the interpretation that the nodal tumor represented a metastatic progression of the known pleomorphic lung carcinoma (which had likely undergone phenotypic drift, losing TTF-1 expression), rather than a new primary head-neck squamous carcinoma. This aligns with the understanding that sarcomatoid carcinomas can lose expression of lineage markers like TTF-1 in metastases.

No adjuvant radiation was given to the neck because the nodal disease was completely resected with clear margins and no extracapsular spread, and the patient had already received high-dose SBRT to the lung. Likewise, systemic therapy was not initiated given the absence of other disease. The patient continued on routine surveillance.

At a follow-up of 5 years after the TORS (and 4 years after salvage neck dissection), the patient remained disease-free. Endoscopic examination of the oropharynx at 5 years post-TORS showed no evidence of recurrent tumor in the PPW or elsewhere (Fig. 3A). A neck CT at the same interval confirmed no residual or recurrent masses at the surgical site and no new lymphadenopathy. Additionally, a follow-up chest CT at 8 years after SBRT (which coincided with 5 years after neck dissection) showed post-radiation fibrosis in the left upper lobe but no sign of active cancer in the chest (Fig. 3B). The patient continues to have no recurrence or metastasis as of the most recent follow-up (approximately 8 years from initial diagnosis). Functionally, he has no swallowing difficulty, no speech impairment, and reports an excellent quality of life.

Figs. 2 and 3 illustrate the imaging findings of the nodal recurrence and the long-term remission status, respectively. Fig. 2 shows the neck CT 10 months post-TORS with the new level IIa node (yellow circle) and no abnormality at the TORS resection site. Fig. 3A shows an endoscopic view of the oropharynx 5 years after TORS, demonstrating normal mucosa of the posterior wall and no evidence of tumor. Fig. 3B presents the corresponding surveillance scans (neck and chest CT) confirming ongoing remission.

This case thus achieved a long-term disease-free survival through localized therapies alone. The patient’s clinical timeline, treatments, and key pathological findings are summarized in Fig. 4, which provides a schematic and histopathological correlation of the metastatic progression from the PPW lesion to the cervical lymph node.

The posterior pharyngeal wall (along with the palatine tonsils) is an unusual site for metastasis partly because these structures lack afferent lymphatic drainage.5) In the absence of direct lymphatic channels, hematogenous dissemination is the most plausible route by which the lung carcinoma seeded the oropharyngeal mucosa.5-7) Our patient’s presentation with a solitary oropharyngeal lesion, in the absence of widespread metastases or early cervical lymph node involvement, strongly supports a bloodborne metastasis to the PPW. The subsequent delayed lymph node recurrence in the neck (level IIa) could represent secondary spread via lymphatic drainage from the oropharyngeal metastasis once it had established - essentially a metastasis of a metastasis. It is also possible that this nodal tumor arose from a small, occult cancer cell deposit that was present in the neck at the time of initial treatment (undetectable on earlier imaging) which then progressed. Retrograde lymphatic spread from the PPW lesion or clonal evolution of a residual microscopic focus are considerations. Direct implantation of tumor cells to the oropharynx via instrumentation (e.g., during the lung biopsy) is exceedingly unlikely in this case, given the timeline and the fact that the PPW mass was the presenting symptom.5,8) Overall, the evidence points to hematogenous spread to the PPW followed by regional lymphatic spread to the cervical node.

This case highlights the marked heterogeneity of pleomorphic (sarcomatoid) carcinoma of the lung. Pleomorphic carcinomas often contain components that can morphologically mimic other tumors (sarcoma, giant cell tumor, etc.) and may show immunophenotypic drift in metastases.3,4,8) In our patient, the primary lung tumor was diagnosed as pleomorphic carcinoma with focal squamous features and was TTF-1 positive initially. The metastatic PPW tumor, while clearly carcinoma, presented an unusual histiocytic-rich histology that made initial diagnosis challenging until immunostains were done. Notably, the nodal metastasis resected 10 months later was histologically classified as squamous cell carcinoma and had lost TTF-1 expression, which could have led to confusion with an independent head-neck primary. However, the overall clinicopathologic context supported a single disease process: the similar poorly differentiated morphology shared by the lung and oropharyngeal tumors, the HPV-negative status of the neck node, the lack of any other primary tumor on thorough work-up (including the negative tonsillectomies), and the fact that level IIa is a typical drainage site for the tonsillar/PPW region. These factors all favoured metastatic progression from the lung origin rather than a second primary oropharyngeal squamous carcinoma. The evolution observed - from a TTF-1 positive pleomorphic carcinoma in the lung and PPW, to a TTF-1 negative squamoid carcinoma in the lymph node - is in line with known tendencies of sarcomatoid carcinomas to undergo phenotypic changes.3,5) Loss of TTF-1 and acquisition of squamous characteristics in metastases have been reported in pleomorphic carcinomas of the lung.3,4) Pathologists evaluating unusual head-neck malignancies should remain aware of this possibility, especially when there is a history of an aggressive carcinoma elsewhere. In ambiguous cases, molecular analyses (e.g., next-generation sequencing for mutational profiling) could be employed to confirm clonality between lesions.3) In our case, the pieces of evidence were sufficient to conclude the metastatic nature of the disease without the need for such testing.

There is no established treatment protocol for oropharyngeal metastasis from lung cancer due to its extreme rarity.5) Reported cases in the literature often have a poor prognosis; many patients succumb within a few months of diagnosis, even with systemic therapy, as such metastases usually signify widespread disease and aggressive tumor biology.7,9) In contrast, our patient exemplifies an oligometastatic presentation in which aggressive local therapy achieved long-term disease control. A few key aspects of management deserve emphasis. First, the use of TORS (transoral robotic surgery) allowed us to achieve a complete resection of the PPW lesion with clear margins while minimizing morbidity. The TORS approach provided excellent three-dimensional visualization and precision in a confined anatomic space that would be challenging to access via open techniques or standard endoscopy.10) The patient avoided more invasive open surgery (which might have required mandibulotomy or pharyngotomy) and had no need for tracheostomy. The rapid postoperative recovery and favorable early healing (Fig. 1D) illustrate the advantage of TORS in managing select oropharyngeal tumors. As demonstrated by the early postoperative endoscopy, the surgical site healed well, reflecting the minimal functional deficit after robotic resection. Second, definitive treatment of the primary lung cancer was crucial.5) We achieved this with SBRT, which in early-stage NSCLC can offer local control rates comparable to surgery. SBRT was an appealing initial approach here, given the patient’s synchronous metastasis - it controlled the lung tumor without delay and allowed us to then focus on the metastatic site surgically. Notably, no systemic chemotherapy was given at any point, yet the patient remains disease-free many years later. This underscores the potential for durable remission in carefully selected patients using curative-intent local treatments alone. Finally, the occurrence of a solitary cervical node metastasis at 10 months prompted timely surgical salvage. The modified neck dissection eradicated the regional disease, and the lack of extracapsular spread boded well for prognosis. The patient’s five-year disease-free survival following these sequential treatments is remarkable for metastatic lung cancer. To our knowledge, this is one of the longest reported remissions for a case of lung carcinoma metastatic to the oropharynx.

In summary, this case demonstrates that an aggressive multidisciplinary approach - combining SBRT for the primary lung tumor, TORS for the oropharyngeal metastasis, and salvage neck dissection for nodal relapse - can yield excellent long-term control in an oligometastatic NSCLC scenario. Curative local therapy should be considered for isolated head and neck metastasis of lung cancer, especially if the primary disease is otherwise controlled. Furthermore, accurate diagnosis (distinguishing metastasis from a second primary) is vital to guide appropriate therapy. Ongoing surveillance is necessary, as late regional metastases can occur, but successful salvage is possible as shown here. This case adds to the scant literature on lung-to-oropharynx metastases and highlights the value of advanced surgical techniques like TORS in achieving curative outcomes with preserved function. Future reports and pooled analyses of similar cases will help define optimal management and prognostic factors for this unusual clinical scenario.