Answer for BIR CoW 07 Jul 2024
ALLERGIC FUNGAL SINUSITIS
Findings
T2 hyperintense mucosal thickening noted involving bilateral maxillary,sphenoidal,ethmoidal and frontal sinuses. T1 iso and T2 hypointensities noted within the bilateral ethmoidal, maxillary, sphenoidal and ethmoidal sinuses. On contrast administration mucosal enhancement noted involving bilateral maxillary sinus, ethmoid sinus, frontal sinus and sphenoid sinus. No abnormal enhancing soft tissue noted within the paranasal sinuses/nasal cavity. Intra and extraconal orbital space appears normal. Pre and retro maxillary fat pads appears normal.
Discussion
Allergic fungal sinusitis is the most common form of fungal sinusitis and is common in warm and humid climates. It occurs in younger, healthier individuals as compared to the other forms of fungal sinusitis. There is often pansinusitis or bilateral involvement of multiple sinuses, with ethmoid involvement being the most common. Acute fulminant invasive fungal sinusitis (AFIFS) occurs predominantly in patients with profound immunosuppression. AFIFS most commonly begins as mucosal inflammation around the middle turbinate. It generally spreads to the maxillary and ethmoid sinuses, followed by the sphenoid sinus Imaging features of Allergic fungal sinusitis : On noncontrast CT, allergic mucin causes hyperintensity and near-complete opacification of the sinus lumens, whose mucosal linings are hypodense. With contrast administration, lack of enhancement in the center or in majority of the sinus helps distinguish AFRS from malignant tumors. Evidence of sinus expansion and osseous remodelling is also commonly observed. Imaging features of Acute fulminant invasive fungal sinusitis include CT findings 1.Unilateral sinus opacification often with focal bone erosion, 2.Soft-tissue thickening of the sinuses and lateral nasal wall mucosa, and Subtle infiltration of perimaxillary fat 3.Marked, unilateral nasal soft-tissue thickening is the most common early CT finding, although it is not specific to AFIFS. MR findings include T1: hypointense inflamed mucosal thickness. It can have multiple T1 appearances. T2 :usually a hyperintense peripheral inflamed mucosal thickness low T2 signal or signal void is due to high concentration of various metals such as iron,manganese and magnesium concentrated by fungal organisms as well as high protein and low free water content in allergic mucin T1 C+ (Gd): The inflamed mucosa typically shows contrast enhancement in allergic fungal sinusitis. no mucosal enhancement noted in invasive fungal sinusitis. Other features: Nonenhancing, hypointense turbinates (the “black turbinate sign”), Sinus opacification, Air–fluid concentration, Obliteration of the nasopharyngeal planes, variable intensity within the sinuses on T1- and T2-weighted images (more likely hypointense on T2), Inflammatory changes in the extraoccular fat and muscles, And leptomeningeal enhancement. The latter two are more common in advanced disease. Occasionally , as in the more chronic forms of invasive sinusitis, intracranial granulomas are also seen. These granulomas generally are hypointense on T1- and T2-weighted images without or with only minimal contrast enhancement. CT often demonstrates the involvement of only one sinus with a hyperintense (“metal-dense”) spot at the center of the fungus ball, often with sclerosis of the adjacent bone. It may be ovoid in shape or assume the contour of the sinus lumen. The fungus ball demonstrates low signal on both T1 and T2-weighted MR secondary to a lack of free water. Non-enhanced CT is often considered the study of choice because intralesional calcifications are also often seen. Differential diagnosis Sinonasal polyposis Sinus fungal mycetoma It represents a fungal colonization without hyperimmune response Usually involving only the maxillary sinus Sinonasal mucocele It has the same chronic expansive features No bone erosions Non-Hodgkin lymphoma Sinonasal mass homogeneously hyperdense on non-contrast CT
References
Gorovoy IR, Kazanjian M, Kersten RC, Kim HJ, Vagefi MR. Fungal rhinosinusitis and imaging modalities. Saudi J Ophthalmol. 2012 Oct;26(4):419-26. doi: 10.1016/j.sjopt.2012.08.009. PMID: 23961027; PMCID: PMC3729552.
Findings
T2 hyperintense mucosal thickening noted involving bilateral maxillary,sphenoidal,ethmoidal and frontal sinuses. T1 iso and T2 hypointensities noted within the bilateral ethmoidal, maxillary, sphenoidal and ethmoidal sinuses. On contrast administration mucosal enhancement noted involving bilateral maxillary sinus, ethmoid sinus, frontal sinus and sphenoid sinus. No abnormal enhancing soft tissue noted within the paranasal sinuses/nasal cavity. Intra and extraconal orbital space appears normal. Pre and retro maxillary fat pads appears normal.
Discussion
Allergic fungal sinusitis is the most common form of fungal sinusitis and is common in warm and humid climates. It occurs in younger, healthier individuals as compared to the other forms of fungal sinusitis. There is often pansinusitis or bilateral involvement of multiple sinuses, with ethmoid involvement being the most common. Acute fulminant invasive fungal sinusitis (AFIFS) occurs predominantly in patients with profound immunosuppression. AFIFS most commonly begins as mucosal inflammation around the middle turbinate. It generally spreads to the maxillary and ethmoid sinuses, followed by the sphenoid sinus Imaging features of Allergic fungal sinusitis : On noncontrast CT, allergic mucin causes hyperintensity and near-complete opacification of the sinus lumens, whose mucosal linings are hypodense. With contrast administration, lack of enhancement in the center or in majority of the sinus helps distinguish AFRS from malignant tumors. Evidence of sinus expansion and osseous remodelling is also commonly observed. Imaging features of Acute fulminant invasive fungal sinusitis include CT findings 1.Unilateral sinus opacification often with focal bone erosion, 2.Soft-tissue thickening of the sinuses and lateral nasal wall mucosa, and Subtle infiltration of perimaxillary fat 3.Marked, unilateral nasal soft-tissue thickening is the most common early CT finding, although it is not specific to AFIFS. MR findings include T1: hypointense inflamed mucosal thickness. It can have multiple T1 appearances. T2 :usually a hyperintense peripheral inflamed mucosal thickness low T2 signal or signal void is due to high concentration of various metals such as iron,manganese and magnesium concentrated by fungal organisms as well as high protein and low free water content in allergic mucin T1 C+ (Gd): The inflamed mucosa typically shows contrast enhancement in allergic fungal sinusitis. no mucosal enhancement noted in invasive fungal sinusitis. Other features: Nonenhancing, hypointense turbinates (the “black turbinate sign”), Sinus opacification, Air–fluid concentration, Obliteration of the nasopharyngeal planes, variable intensity within the sinuses on T1- and T2-weighted images (more likely hypointense on T2), Inflammatory changes in the extraoccular fat and muscles, And leptomeningeal enhancement. The latter two are more common in advanced disease. Occasionally , as in the more chronic forms of invasive sinusitis, intracranial granulomas are also seen. These granulomas generally are hypointense on T1- and T2-weighted images without or with only minimal contrast enhancement. CT often demonstrates the involvement of only one sinus with a hyperintense (“metal-dense”) spot at the center of the fungus ball, often with sclerosis of the adjacent bone. It may be ovoid in shape or assume the contour of the sinus lumen. The fungus ball demonstrates low signal on both T1 and T2-weighted MR secondary to a lack of free water. Non-enhanced CT is often considered the study of choice because intralesional calcifications are also often seen. Differential diagnosis Sinonasal polyposis Sinus fungal mycetoma It represents a fungal colonization without hyperimmune response Usually involving only the maxillary sinus Sinonasal mucocele It has the same chronic expansive features No bone erosions Non-Hodgkin lymphoma Sinonasal mass homogeneously hyperdense on non-contrast CT
References
Gorovoy IR, Kazanjian M, Kersten RC, Kim HJ, Vagefi MR. Fungal rhinosinusitis and imaging modalities. Saudi J Ophthalmol. 2012 Oct;26(4):419-26. doi: 10.1016/j.sjopt.2012.08.009. PMID: 23961027; PMCID: PMC3729552.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!