Diagnostic histological features of metastatic lymph nodes in adenosquamous carcinoma

Laryngeal adenosquamous carcinoma (ASC) is a rare malignancy, and the problems in true diagnosis of this entity are well known. In this paper, we describe a case of ASC and discuss its distinct histopathology in metastatic lymph nodes. A heavy smoker man presented with a progressive neck mass. Based on incisional biopsy, diagnosis of squamous cell carcinoma (SCC) was made and total laryngectomy with bilateral radical neck dissection was performed. Sections of primary tumor showed a well-differentiated SCC. However, lymph node metastases had a distinct feature of glandular structures. Further investigation with Mayer's mucicarmine stain confirmed the presence of rare scattered glands in primary tumor and the final diagnosis was changed to ASC. Adenosquamous carcinoma is a distinct entity and must be distinguished from the common SCC of larynx. As a result, when a lesion with diagnosis of squamous cell carcinoma shows evidence of glandular differentiation in a subsequent biopsy or in nodal metastases, more investigation is necessary. Moreover, the glandular structures in primary tumor, as in this case, may be rare and inconspicuous. Therefore, we suggest the precise evaluation of metastatic lymph nodes for any laryngeal tumor with diagnosis of SCC. This helps to make appropriate therapeutic decisions with respect to the aggressive behavior of ASC and its high propensity for lymph node metastasis.