5- DISCUSSION
We presented an extremely rare case of a LCS with cervical LNMPTC. To our best knowledge, this is the first case reported in literature, where these two malignancies coexist. In 2012 Buda et al 22, reported one case of a LCS arising from cricoid cartilage associated to a PTC. Vahidi et al 23 reported a case of a LCS arising from thyroid cartilage with an incidental PTC. Lymph node metastasis was absent in both reports.
As mentioned before, LCS are rare tumors, which often require surgical treatment. The key in order to choose the appropriate treatment is to balance the oncological with the functional outcomes. The goal in these patients should be to remove the tumor with adequate margins avoiding local recurrences or distant metastasis, trying to preserve the voice and normal swallow. For this reason, surgeons have described different surgical techniques, including minimally invasive local resections, laser procedures, hemicricoidectomy, partial laryngectomies with reconstruction or not, and more aggressive techniques like total laryngectomy. Theoretically, less aggressive techniques are indicated for low-grade and not extensive tumors, and total laryngectomy is the choice for high-grade, extensive tumors and recurrences. In our case we decided to perform total laryngectomy, given the extension of the lesion24,25. In our systematic review, laryngectomy (total or partial) was the treatment of choice in most of the patients, followed by local excision or laser removal of the tumor. Survival appeared to be lower in those patients treated with total laryngectomy, and this may have an explanation, probably because those candidates to this surgical technique might have more advanced tumors.
Cervical metastases of CS are rare, and neck dissection should be performed only if radiological or clinical evidence of disease is present. In our case, neck imaging revealed pathological nodes, so bilateral neck dissection was performed. Besides, due to tumor size and location, total thyroidectomy was performed. Treatment of PTC is debatable. Some authors advocate for active surveillance in cases of thyroid microcarcinoma or occult PTC 26. In other cases, based upon different risk factors, a thyroid lobectomy or total thyroidectomy can be the option 18. Different authors described the appearance of incidental metastatic PTC in neck dissections of non-thyroidal surgery, with a prevalence up to near 2%27. Thyroid carcinoma in cervical lymph nodes can have two possible origins. First, the possibility of malignant transformation of ectopic or heterotopic thyroid tissue. This fact can be explained due to anomalies in the migration of the thyroglossal during embryologic development. Also, alterations in development of the pharyngeal pouch endoderm can explain the presence of ectopic tissue in cervical lymph nodes 28. Although ectopic thyroid malignancies commonly appear together with tumoral native tissue, in some cases a benign thyroid gland was found with ectopic PTC in different upper body locations including the neck 29. Second, the appearance of PTC lymph node metastasis from thyroid is not unfrequent in patients with thyroidal cancers as reported by So et al. in up to 90% of the cases 30. This fact is associated with locoregional recurrence and a poor prognosis. In our systematic review, few cases reported cervical metastasis of CS 31-33. In none of them PTC lymph node metastasis was found.
Comparing our systematic review with the biggest series previously published 3,12, in general, our results are in agreement, regarding tumor grading, anatomical site, tumor size, treatment modality, symptomatology and follow-up with them.
Thus, LCS are more common in men, affect people in their sixties, the main symptoms are dyspnea and hoarseness, CT scan is the most common imaging technique for diagnosis, cricoid cartilage is the most frequent location, total laryngectomy is the most commonly used surgical technique, well-differentiated CS is the most frequent histopathologic finding, distant metastases are rare and survival is related to histologic differentiation, anatomical involvement, surgical technique and recurrence.
The main limitation for this systematic review was the heterogeneity in data reporting, primary and secondary outcomes and follow-up. The search included articles from 1968 to 2020, and clinical information in different series were unavailable or inaccurate. This fact made that some series, had to be excluded from our systematic review34-40 despite the high number of cases reported.
In conclusion, with this systematic review we provide a reliable general view of different aspects of LCS. These tumors are rare, and generally with a better prognosis than other laryngeal tumors. We also presented an extremely rare case of coexistence of LCS and cervical LNPTC. This is the first case reported in literature where this 2 entities appear simultaneously in a patient.