Calcitonin-secreting Neuroendocrine Tumor of the Larynx, a Diagnostic Challenge of a Rare Neoplasm: a Case Report and Literature Review

Background: Laryngeal neuroendocrine tumors (NETs) represent less than 1% of all malignancies originating from the larynx and available data are limited on case reports. Calcitonin secreting laryngeal NETs are extremely rare and serial dosing of calcitonin in these patients might reveal early relapse or persistence.

Case Description: We report the case of a 71-year-old woman with persistent pharyngodynia who underwent surgery for an initial diagnosis of small cell undifferentiated neuroendocrine carcinoma (SCUNC) of the larynx (on the epiglottis extended to the left glosso-epiglottic vallecula). The immunohistochemical profile showed the presence of synaptophysin, neuron-specific enolase (NSE), chromogranin A, pan-cytokeratin, including cytokeratin AE1-AE2, and focally calcitonin. The circulating NSE was 13.4 microg/L (normal level <12.5 microg/L) and the basal serum level of calcitonin was 237 pg/mL (normal level <11.5 pg/mL). The patient was started on first-line carboplatin-etoposide chemotherapy because of early relapse to an axillary lymph node. After 4 cycles of treatment, a radiological stability and metabolic response were demonstrated together with a drastic decrease of circulating serum level of calcitonin (from 237 to 57.9 pg/mL). During the follow up, locoregional relapse of disease occurred, associated with an increase of serum calcitonin (89.3 pg/mL). Disease further progressed on and rechallenge with platinum-etoposide chemotherapy was administered, during which clinical progression was confirmed. Due to the lack of response, a revision of the histology was performed and concluded for a definitive diagnosis of moderately differentiated G2 NET, with a Ki-67 index of 22.6%.

Conclusions: This is the eighth case report of laryngeal NET, highlighting the challenge in pathological differential diagnosis and therapeutic strategies. The association with elevated serum calcitonin and the trend of this parameter during clinical progression suggest a role of this marker in the diagnosis and early identification of recurrent laryngeal NETs.