 Hello everyone, Myself Dr. Jyoti, PGIMS Rottak, my topic for paper presentation is primary sclamaceous carcinoma of the frontal sinus introduction. Primary frontal sinus carcinoma is extremely rare and accounts for only 0.009 to 0.03% of all the head and neck cancers. The complex anatomy of the region and the rare occurrence of these tumor pose diagnostic and therapeutic challenges. Sclamaceous carcinoma is the most common histological subtype. It most commonly affects patient in 6-7th decade of life with male predominance. The maxillary sinus is most commonly affected side followed by nasal cavity and the ithmoid sinus. Primary sclamaceous carcinoma of the sphenoid sinus and frontal sinus are rare. The treatment modalities vary depending on the tumor histological subtype, location and extent of the disease and includes surgery, radiation, chemotherapy or a combination of these modalities. The prognosis of the patients largely depend on tumor histology, location and stage. Imaging CK and MRI helps in the assessment of tumor size, nature, extent and invasion. CT is the most commonly used imaging modality because of its wider availability, easy access, lower cost and better anatomical details. CT is particularly effective in detecting calcification and bone invasion. Intralesional calcification is seen in adenocarcinoma, inverted papilloma, fungal sinusitis and dentizaris tumor. In contrast MRI provides higher contrast resolution and good characterization of soft tissue component. Malignant tumors usually exhibit hyper intensity on T2 weighted image and hypo to iso intensity on T1 weighted image. On T2 weighted image machinous or cartilaginous tumor show hyper intensity and tumor with fibrosis, calcification or flow word show hyper intensity. On T1 weighted image hyper intensity within a tumor is indicative of the presence of methemoglobin, melanin, lipid, protein and mineral elements. DWIN-ADC captures the degree of brownian movement of water molecules and tissues which serves as a useful imaging biomarker. Low ADC lesions with strong diffusion restriction indicate hypercellularity, abscess or hemorrhage whereas high ADC indicate hypercellularity, mucus, cartilage or fluid. Therefore DWIN-ADC measurement is useful to differentiate between benign and malignant lesions. CEMRI is helpful in detecting perineural spread and neural invasion. Case Report A 52 year old female was admitted with the chief complaint of chronic headache since 5 years. The intensity and frequency of headache was worsened in last 3-4 months. On physical examination there is drooping of left upper eyelid however the vision was normal. The skin overlying the frontal sinus appear normal with no signs of inflammation. Neurological examination found no deficit. CT revealed a soft tissue density mass in the left frontal sinus with erosion of the surrounding bone. MRI demonstrate a mass lesion in left frontal sinus which was enhanced by gadolinium. The tumor was adhered to the posterior dural surface and extending into adjacent ethmoid sinus and roof of orbit. There was no evidence of invasion into nasal cavity or intradural space. FDG packed of the whole body showed accumulation only in the mass of the frontal sinus via sweet from the mass lesion favored scramiscell carcinoma. Bone window section illustrate destruction of posterior wall of frontal sinus and erosion of the roof of left orbit. Soft tissue window reveals soft tissue mass in left frontal sinus with extension into frontal lobe and the mass seems to be extending into the orbit involving LPS and superior rectus muscle complex. CMRI was performed and demonstrated enhancing mass lesion in the left frontal sinus with dural enhancement along left frontal lobe. However, no evidence of brain parankimal involvement seen. DWN ADC values reveals true diffusion restriction in the mass lesion. CESITAL and CORONAL section shows mass lesion with involvement of superior rectus and LPS muscle complex in the left orbit. Discussion. The incidence of primary frontal sinus carcinoma is extremely low. Approximately 3% of all head and neck cancer originate in the nasal and perineasal sinuses. The annual incidence is 1 to 3 cases per 1 lakh population. Primary frontal sinus carcinoma accounts for 0.3 to 1% of the nasal and the perineasal sinus cancers. In this case, patient came to our department for evaluation of perineasal sinus infection as provisional diagnosis. In this COVID pandemic, we were also considering the possibility of mucus mucomycosis as invasive fungal sinusitis can also present like this. But history of COVID infection was negative, patient was non-diabetic and no history of recent steroid intake was given. NCCT PNS was performed and we found soft tissue mass involving left frontal sinus with bony destruction indicating towards aggressive pathology. Other sinuses were grossly normal. The lesion was involving orbit. CEMRI was performed to illustrate brain and orbital involvement. The lesion showed enhancement with dural involvement. However, no abnormal signal intensity was noted in frontal lobe. FES was performed and biopsy was taken. Histopathological reports suggested the diagnosis of scour micelle carcinoma with specific tumor markers. After confirming the diagnosis, FDG PET was done to look for metastasis and treatment plan. Abnormal uptake was only seen in the left frontal sinus. Patient was planned for surgery and further treatment. Generally, nasal and perineasal carcinomas are treated with multi-modality combined therapy such as surgery and radiotherapy with or without chemotherapy. However, the anatomical complexity of the frontal sinus and surrounding structures makes the treatment difficult and the actual 5-year overall survival rate for perineasal cancer is about 40-50% and the prognosis for frontal sinus carcinoma is also poor. Conclusion Although the radiological differentiation of sinonasal malignancy is very difficult because of the similarity of imaging findings, the tumor location, growth pattern into adjacent bone, tumor homogeneity, internal signal intensity, contrast enhancement pattern and DWN ADC measurement may facilitate inadequate diagnosis. CT and MRI are useful tools for pre-treatment evaluation of the characterization, localization and distribution of the malignant sinonasal tumors. References