Malignant sinonasal carcinomas are a rare entity comprising less than 1% of all cancers and around 3% of all head and neck malignancies seen in humans. Among these 15-20% are transitional cell carcinoma also known as non keratinizing carcinoma of sinonasal tract. We are reporting the case of a 45 years female with history of nasal obstruction and epistaxis. A contrast enhanced computed tomography (CECT) was done which showed mucosal thickening in the right nasal cavity. Endoscopy assisted biopsy was taken which revealed non keratinizing carcinoma (transitional type). Very few reported cases of this type of malignancy was found. A possible reason could be multiple synonyms like cylindrical cell carcinoma, Schneiderian carcinoma and transitional cell carcinoma.

INTRODUCTION

Nonkeratinizing carcinoma (NKC), comprising of about 15-20% of all malignant sinonasal tumors, is a rare entity, with very few cases reported so far. [1] According to the World Health Organization (WHO) classification, it has many synonyms, including, Schneiderian carcinoma, transitional cell carcinoma, cylindrical cell carcinoma, Ringertz carcinoma, and respiratory epithelial carcinoma. [2]

CASE REPORT

A 45-year-old female, non-smoker, presented with progressively worsening right nasal obstruction for the last one year and recurrent epistaxis for the last one month. There were no other symptoms. The clinical examination revealed a deviated nasal septum and congested nasal mucosa in the left side. Contrast-enhanced computed tomography (CECT) of the nose and paranasal sinuses revealed, mucosal thickening of the left nasal cavity, without any mass or abnormality in any of the paranasal sinuses [Figure 1] and [Figure 2]. The nasopharynx was also free from tumor. Endoscopy-assisted removal of the mucosal thickening was done. Histopathology showed the tissue partly lined by respiratory epithelium, with the underlying stroma infiltrated by malignant cells, forming islands and ribbon-like patterns [Figure 3],[Figure 4],[Figure 5] and [Figure 6]. The individual cells had a high nuclear: cytoplasmic (N: C) ratio, with pleomorphic, hyperchromatic nuclei and prominent nucleoli. Numerous mitoses were seen. Occasional foci of keratinization were also seen. She is now under medical follow-up.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}

DISCUSSION

Nonkeratinizing squamous cell carcinoma (SCC) or transitional cell carcinoma of the sinonasal tract is a rare entity. The annual incidence of malignant sinonasal carcinoma is 3.5 per 100,000 population. [3] Of this 15-20% is transitional carcinoma. [1] According to the WHO classification, it has many synonyms including, Schneiderian carcinoma, cylindrical cell carcinoma, Ringertz carcinoma, and respiratory epithelial carcinoma, [2] as the tumor is composed of malignant proliferating cells derived from the sinonasal respiratory (Schneiderian) epithelium. [4] The name cylindrical cell carcinoma was first coined by Ringertz in 1938, [5] and was recommended as the preferred term by Shanmugaratnam in the WHO classification of 1991. [6]

Sinonasal carcinoma (Squamous cell carcinoma and adenocarcinoma) are strongly associated with environmental factors, including tobacco, alcohol, and occupational exposure (e.g. to heavy metal, nickel, and chromium), and with workers in the leather, textile, and wood industries. [2],[7],[8],[9],[10] Sinonasal tract malignancies most commonly affect the maxillary sinus (about 60%), followed by the nasal cavity (about 22%), ethmoid sinus (about 15%), and frontal and sphenoid sinuses (3%). [2],[8],[9],[10] In this case, no association with the risk factors was found. A strong etiological relationship between nonkeratinizing carcinoma (NKC) and the human papilloma virus (HPV) has been suggested by some recent studies. [11] Many of these tumors show immunoreactivity for p16. [4]

Gross appearance of the tumor in most cases is that of an exophytic growth with a smooth or corrugated surface arising from the maxillary antrum or lateral nasal wall or ethmoid sinus. [12],[13] In our case the gross appearance was that of mucosal thickening of the lateral nasal wall.

Nonkeratinizing carcinoma is listed by the WHO as a variant of SCC. Histopathologically, NKC is characterized by a plexiform or ribbon-like growth pattern, with papillary fronds of stratified cells, which at low magnification are often confused with inverted papilloma. [4] The tumor cells form palisading arrangements, perpendicular to the underlying basement membrane. [4] The cells show an atypical nuclear feature, with increased mitotic count. [4] The tumor usually shows pushing margins with focal infiltration of the stroma. [4] Foci of the squamous metaplasia are not uncommon, and when extensive, these tumors may be indistinguishable from SCC. [4] In addition, the term cylindrical cell carcinoma must be preferred to nonkeratinizing squamous cell carcinoma, because ′pure′ cylindrical cell carcinomas, without any squamous cell component, carry a better prognosis than conventional SCCs. [14] Although identified as nonkeratinizing, there are often small keratin pearls interspersed within the proliferations and some may form surface keratin that fills the cystic spaces. [2],[15] Similar features were seen in our case.

If SCC is confined to the nasal cavity, the five- and ten-year survival rates are in the range of 80%. Involvement of the paranasal sinus adversely affects the prognosis. [2],[9],[10],[16] Cervical lymph node metastasis develops in up to 20% of the patients, with rare distant metastasis. [2],[10] Treatment depends on the tumor location and extent. [2] T1 and T2 nasal tumors are treated by surgical resection, while T3 and T4 tumors receive postoperative radiotherapy. Various surgical approaches like lateral rhinotomy or medial maxillectomy or an en bloc ethmoidectomy are done for superior and lateral nasal cavity carcinomas. [17] Paranasal sinus tumors are managed by radical en bloc surgical resection followed by radiotherapy. [8],[9],[10],[16] Chemotherapy may be used as a neoadjuvant or postoperatively. [2] Our case underwent endoscopic lateral rhinotomy with a close follow-up.

Conclusion

Nonkeratinizing squamous cell carcinoma of the sinonasal tract is a very rare entity. Only few cases have been reported previously, which may be because it has many synonyms like, cylindrical cell carcinoma, Schneiderian carcinoma, and transitional cell carcinoma. In most of the reported cases, it is not associated with any risk factors and presents in young to middle-aged females, as progressive nasal obstruction. The prognosis is good in pure form and surgical resection followed by radiotherapy is the treatment of choice.