Introduction:
Cancer in the nose and surrounding spaces is rare, constituting approximately 3 percent of cancers in the head and neck area. Sinonasal undifferentiated carcinoma (SNUC) is a rare and aggressive type of cancer that occurs in the nose and the sinuses, which are air-filled cavities near the nose. These cancers originate from the Schneiderian epithelium (a special type of epithelium that lines the paranasal sinuses and nasal cavity) or nasal ectoderm of the paranasal sinuses. They are fast-growing tumors that extend beyond their usual boundaries. Diagnosis involves immunohistochemical analysis to confirm their epithelial origin. The current treatment includes radical resection, radiation therapy, and chemotherapy. Despite aggressive management, the mean survival rate is meager and has a poor prognosis.
What Is the Cause of Sinonasal Undifferentiated Carcinoma?
These cancers originate from the Schneiderian epithelium, a type of respiratory epithelium that lines the paranasal sinuses and the nasal cavity. The cause is unknown and may be associated with a history of cigarette smoking and occupational exposure to carcinogens, such as in coal mines and chrome plating factories. In some cases, patients who have undergone radiation therapy due to retinoblastoma (a type of cancer affecting the retina, which is present behind the eye) have developed SNUC later.
What Are the Clinical Features of Sinonasal Undifferentiated Carcinoma?
The clinical features of sinonasal undifferentiated carcinoma include:
-
Nasal symptoms are characterized by persistent nasal congestion, a runny nose, a blocked nose, and nosebleeds (epistaxis) due to damage to the blood vessels caused by the infiltrating tumor. Additionally, there can be nasal obstruction or infection.
-
Pain and swelling on the affected side.
-
Limited mouth opening, often accompanied by pain.
-
Change in the sense of smell occurs due to the impact on the olfactory structures of the nose.
-
A visible swelling or palpable mass in the nose or sinus area.
-
Due to the aggressive nature of the tumor, it can exert pressure on surrounding areas, leading to headaches, eye pain, vision changes, proptosis (bulging of the eye), periorbital swelling, and diplopia (double vision).
-
Cranial nerve palsies (lack of functioning of the nerves which emerge directly from the brain).
What Is the Diagnosis of Sinonasal Undifferentiated Carcinoma?
The diagnosis of sinonasal undifferentiated carcinoma includes:
Clinical Findings: The most common symptoms include pain, swelling around the affected areas, nasal congestion, limited mouth opening, along with changes in the sense of smell. Clinically, ulcerated proliferative growth is observed, and the surface may be covered with necrotic tissue accompanied by bleeding or pus discharge. Kadish staging is typically used in this cancer, which involves:
-
Group A: Confinement of the tumor to the nasal cavity.
-
Group B: Involvement of the tumor in the nasal cavity and paranasal sinuses.
-
Group C: Involvement of the tumor beyond the paranasal sinuses.
-
Group D: Involvement of the tumor in cervical lymph nodes or the occurrence of distant metastasis.
Imaging Findings: Imaging techniques, aided by computed tomography (CT) scans, reveal large enhancing lesions, and magnetic resonance imaging (MRI) aids in visualizing the tumor size and its extension. These scans show destruction of the sinus walls involving paranasal sinuses, orbital bones, and the cranial cavity's penetration. The tumor may also extend intracranially. In the case of the anterior cranial fossa, it may affect the optic tracts, causing visual impairment.
Microscopic Findings: Pleomorphic undifferentiated epithelial cells are observed as trabaculae or nests, which are separated by thin fibrous connective tissue septae. The cells exhibit variations in size and shape. Some cells display amphophilic cytoplasm (appearing bluish-red after Hematoxylin and Eosin (H&E) staining), accompanied by hyperchromatic (darkly stained) round to oval nuclei. Nucleoli, which are dense structures within the nucleus, may or may not be present. The nucleoli are prominently visible in certain areas, with nuclei resembling small sacs. Squamous cells were present in some areas, along with areas of necrosis where cell death occurred. Additionally, regions are characterized by increased mitotic activity, indicating rapid cell division.
Immunohistochemical Findings: This technique involves detecting specific proteins in a tissue sample. It utilizes immunology and histology to identify particular molecules within the given sample. Immunohistochemical features of SNUC include:
Positive Markers:
-
Cytokeratins 7, 8, and 19: These proteins are found in the epithelial cell cytoskeleton, indicating their epithelial origin.
-
Neuron-Specific Enolase (NSE): This indicates the presence of neuron-like cells.
Negative markers:
-
S-100: This protein is utilized to identify neural crest origin, which is negative in the case of SNUC.
-
Vimentin: This protein is associated with mesenchymal cells and is negative in the case of SNUC.
What Is the Differential Diagnosis of Sinonasal Undifferentiated Carcinoma?
The differential diagnosis of sinonasal undifferentiated carcinoma includes:
-
Intraosseous expansile radiolucent lesions, such as central giant-cell granulomas (benign aggressive lesions that affects the jaw),
-
Developmental odontogenic cysts like dentigerous cysts (a cyst in the crown portion of the unerupted tooth) and odontogenic keratocyst (benign aggressive cysts in the dental tissue).
-
Odontogenic tumors like ameloblastomas (locally aggressive benign tumors which affect the jaws).
-
Mixed radiopaque–radiolucent intraosseous lesions, such as benign fibro-osseous lesions (involving connective tissue and bones).
-
Lesions of connective tissue origin, including nodular fasciitis (a soft tissue tumor that occurs in the connective tissue) or myofibroma (a rare benign tumor that occurs from myofibroblasts involved in wound healing).
-
Olfactory neuroblastoma (a tumor that occurs in the olfactory nerve cells).
-
Sinonasal neuroendocrine carcinoma (SNEC, a type of cancer that occurs from the neuroendocrine cells, which are specialized cells consisting of nerve and hormonal cells of paranasal sinuses and nasal cavities).
What Is the Management of Sinonasal Undifferentiated Carcinoma?
Due to the rarity of the cancer, standardized protocols have not been established. The management involves a team of surgeons, oncologists, and radiation oncologists. Given the complex head and neck anatomy, complete removal of the tumor with wide margins is not always feasible. As a result, management requires aggressive therapies, including surgical resection combined with adjacent radiotherapy or chemotherapy. Follow-up treatments encompass the use of eye prostheses, dental prostheses, as well as regular MRI scans or tissue biopsies for monitoring.
Conclusion:
In conclusion, sinonasal undifferentiated carcinomas are rare malignancies characterized by their aggressive nature. Due to their rarity, they present diagnostic and management challenges. This necessitates a multidisciplinary approach involving surgery, chemotherapy, or radiotherapy. The prognosis of Sinonasal Undifferentiated Carcinoma is very poor due to its aggressive infiltrating nature; however, early intervention can lead to successful outcomes.
