Rare Malignancies of Sinonasal Tract

Background Sinonasal malignancies are an uncommon group of tumors among the head and neck cancers. Among this group, there are certain tumors which are even lesser in number. These group may include varied histologies but are rare. The rarity of these tumors makes it difficult to understand their clinical course and to have a standard treatment guideline. We sought to present our experience with these rare tumors of sinonasal tract in regard to treatment and survival outcome.

Methods A retrospective study was performed among the rare tumors from the anterior skull base tumor database of our institute maintained prospectively from 2007 to 2016. Here, we present our experience on rare tumors of sinonasal tract. These tumors were analyzed on the basis of tumor epicenter, staging, treatment modalities, recurrence pattern, and survival.

Results Out of 1,205 total cases in our database, 276 cases were identified to have rare malignancies of sinonasal tract which accounts for around 23% of all the cases in our skull base database. Sarcomas with its various subtypes have been found to be most common among this group (48%) followed by sinonasal teratocarcinoma, melanoma. Various other histologies encountered are myoepithelial carcinoma, sebaceous gland carcinoma, chordoma, hemangiopericytoma, NUT midline carcinoma. Neuroendocrine malignancies, olfactory neuroblastoma, adenocarcinoma, adenoid cystic carcinoma, and SCC were not included in this list. Around 80% of the rare tumors were treated with curative intent, whereas 15% went for palliative management. Surgery followed by radiotherapy was the treatment modality used in majority (60%). Neoadjuvant chemotherapy (NACT) was given in 34 cases (12%), out of which 22 cases showed either partial or complete response. Recurrence was seen in 21% out of which 65% recurred locally. Five-year OS and DFS rates were 74.9 and 55.2%, respectively. NUT midline carcinoma fared the worst among all the groups with poorer survival.

Conclusion The management varies depending on the histology, but multimodality treatment seems to provide a better outcome. However, owing to their rarity, multi-institutional study needs to be planned so that adequate number of cases can be studied and a standard treatment modality can be established.

Table 1 Histological distribution

Histologies	Number (%)
Sarcoma	133/276 (48.3%)
SNTCS	29/276 (10.5%)
Melanoma	28/276 (10.1%)
Lymphoma	21/276 (7.5%)
Poorly differentiated carcinoma	17/276 (6.1%)
Myoepithelial carcinoma	13/276 (4.7%)
Chordoma	11/276 (4%)
Sebaceous gland carcinoma	10/276 (3.6%)
Hemangiopericytoma	09/276 (3.2%)
NUT midline carcinoma	05/276 (1.8%)