A Rare Case of Metastases to Paranasal Sinus From Colonic Adenocarcinoma

Metastases of malignant tumors to the nasal cavity and paranasal sinuses are very rare. Metastases to these locations are usually solitary and produce similar symptoms to those of a primary sinonasal tumor. Pain, nasal obstruction, and epistaxis are the most common symptoms. Although any malignancy could potentially lead to metastasis to the paranasal sinuses, colo-rectal malignancy metastasizes to this site is rare. We report a case of metastatic adenocarcinoma of colorectal origin to the paranasal sinuses in a 55-year-old female who was initially diagnosed with adenocarcinoma of the colon with lung and liver metastasis. She subsequently developed metastasis to left ethmoidal and sphenoidal sinuses during treatment. A histologic study of the surgical specimen from the sinonasal cavity demonstrated a tumor identical to the patient’s prior primary tumor of the colon. The sinonasal neoplastic tissue showed marked positivity for carcinoembryonic antigen and expressed cytokeratin 20, which differentiates metastatic colonic adenocarcinoma from primary intestinal-type adenocarcinoma (ITAC). She received palliative radiation therapy but died three months after the diagnosis. These subsets of patients have a poor prognosis. In the majority of patients, palliative therapy is the only possible treatment option. Nevertheless, whenever possible, surgical excision either alone or combined with radiotherapy may be useful for palliation of symptoms and, rarely, to achieve prolonged survival.


Introduction
The overall incidence of primary adenocarcinoma of the nasal cavity and paranasal sinuses probably accounts for 10% to 20% of all sinonasal malignancies [1]. Most of these tumors are of salivary gland origin. Some tumors are of rare patterns and have histology similar to those of adenocarcinoma of the colon. Metastases of malignant tumors to the nasal cavity and paranasal sinuses are very rare. Incidences of these metastases are common in the 50 and 60 years age group of men and 60 and 70 years age group of women [2]. A review of literature on tumors of paranasal sinuses reports very few cases of sinonasal metastases from colorectal carcinoma [3][4][5][6][7][8].

Case Presentation
Our patient is a 55-year-old female who presented initially to the general surgery clinic in March 2016 after noticing altered bowel habits for a duration of two months. Her past medical history was associated with type 2 diabetes mellitus and hypertension. She had no previous surgical history, no prior colonoscopies, and no family history of colon cancer. Her only gastrointestinal complaint was the changes in the bowel pattern. There was no history of any melena, hematochezia, or weight loss. A colonoscopy demonstrated a splenic flexure mass obstructing the transverse colon lumen and biopsies of the lesion revealed moderately differentiated adenocarcinoma ( Figure 1).   She continued on palliative chemotherapy but succumbed subsequently after three months of palliative radiotherapy due to progressive disease and complications.

Discussion
The most common presentation of symptoms in primary and metastatic malignancy of nasal cavity and paranasal sinuses are facial pain, recurrent epistaxis, and nasal obstruction [9,10]. It is important to distinguish between primary and metastatic malignancies. Most challenging is to differentiate between histology of colonic metastases to these sites from primary sinus adenocarcinomas, more specifically the colonic variant of intestinal-type adenocarcinoma (ITAC) [11].
Primary ITAC is a rare primary malignancy of the nasal cavity and paranasal sinuses. Generally linked to occupation-related hazard, especially with wood dust exposure, but sometimes occurs sporadically [12]. As the histology of the ITAC-colonic variant is difficult to differentiate from metastatic colorectal cancer, therefore, a diagnosis of metastatic adenocarcinoma from these sites requires correlation with any prior history of colorectal cancer. Immunohistochemical studies of the biopsy specimen play an important role to formulate the diagnosis. Positivity for CDX2, CK20, and negativity for CK7 differentiates metastatic colonic adenocarcinoma from ITAC [11,13]. The CK20+/CK7− immunoprofile is considered to be specific for colorectal epithelial tumors [14].
In 1940, Batson postulated that through the low-pressure valveless system connecting deep pelvic veins, intercostal veins, vena cava, and the azygous system, retrograde metastasis to nasal and paranasal sinuses occurs, during increased intrathoracic and abdominal pressure [15].
Nasal and paranasal metastases from colorectal cancer are associated with poor outcomes. None of the cases reports five-year survival from the diagnosis of these metastases. All cases were treated with palliative radiotherapy to the nasal and paranasal region [10,11,16]. The mean survival post-palliative radiotherapy was between 2 and 18 months after diagnosis of the metastases [11,16].

Conclusions
In conclusion, paranasal metastasis is a rare condition and it is important to be differentiated from primary ITAC. The presence of paranasal metastases, unlike ITAC, represents advanced disease and carries a grave prognosis. These types of patients should be managed symptomatically with palliative radiation therapy or chemotherapy with the best supportive care.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the