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Radiology Quiz Case 4—Diagnosis

Radiology Quiz Case 4—Diagnosis Diagnosis: Allergic fungal sinusitis (AFS) of the right sphenoidal sinus Allergic fungal sinusitis is generally recognized as a disease that is distinct from other forms of fungal sinusitis. It most commonly presents in adolescents and young adults, with approximately two thirds of patients reporting a history of allergic rhinitis, and half reporting a history of asthma. Clinical presentation varies from subtle nasal obstruction and crusting to extensive polyposis, chronic sinusitis, acute visual loss, proptosis, and facial dysmorphia. The pathogenesis of AFS is unclear, but immunologic and histologic data suggest that it represents an immunologically mediated disorder rather than an infectious entity. Cultures from patients with AFS most commonly yield organisms from the dematiaceous family of fungi, including Bipolaris.1 Bent and Kuhn2 identified 5 common characteristics (ie, type I hypersensitivity, nasal polyposis, characteristic radiographic findings, eosinophilic mucin without invasion, and positive fungal stain) among 15 cases of AFS. The differential diagnosis of fungal sinusitis is generally divided into invasive and noninvasive forms.3 Invasive disease can be acute (fulminant), characterized by invasion of mucosa, submucosa, and blood vessels by fungal hyphae, most commonly of the Mucorales order or Aspergillus. Patients with invasive disease are usually immunocompromised and require radical surgical debridement. Chronic indolent invasive sinusitis results in noncaseating granulomas that lead to regional tissue invasion in immunocompetent hosts.4 Noninvasive disease includes AFS and mycetomas (paranasal sinus fungal balls). The presenting signs and symptoms of mycetomas, which may be similar to those of AFS, include nasal congestion, a history of chronic sinusitis, rhinorrhea, facial pain, and proptosis. Mycetomas more frequently present in only 1 sinus. Also, they show a chronic inflammatory response in mucosa adjacent to fungal elements (with lymphocytes, plasma cells, and mast cells), and allergic mucin is absent.5 Other diseases that mimic isolated sphenoidal fungal sinusitis are mucoceles and neoplasms.6 Allergic fungal sinusitis has been shown to have characteristic radiographic features. The disease is usually unilateral and affects multiple sinuses. Noncontrast CTs frequently reveal scattered central areas of high attenuation within the involved sinuses. Bone windows, however, can be variable, with a homogeneous ground glass appearance, a starry sky pattern of calcium deposits, or an irregular linear pattern of increased attenuation. Postcontrast T1-weighted MRIs show areas of characteristic hypointense signal that correspond with the regions of high attenuation on CTs. The periphery of involved sinuses will show high signal characteristics as a result of inflammation, especially after the administration of gadolinium–pentetic acid contrast. T2-weighted MRIs will reveal a central signal void in affected sinuses and an intense high peripheral signal. With AFS, evidence of remodeling and destruction of bony sinus walls, likely from pressure atrophy, is often visible on both CTs and MRIs.4,7 Computed tomograms and MRIs of our patient revealed many of these features. An axial CT without contrast (Figure 1) showed a large right sphenoidal mass with several hyperattenuated central regions. A postcontrast T1-weighted MRI (Figure 2) showed multiple regions of hypointense signal within the mass, and a T2-weighted MRI (Figure 3) revealed a signal void within the sinus. Both MRIs demonstrated a narrow, hyperintense periphery of inflamed mucosa. Figure 1. View LargeDownload Figure 2. View LargeDownload Figure 3. View LargeDownload Careful review of CTs and MRIs can help to rule out other differential diagnoses. Fulminant invasive fungal sinusitis reveals mucosal inflammation, with enhancement of the dura or orbits, on CTs and MRIs. Indolent invasive disease leads to mucosal inflammation and bone destruction on CTs as well as to hyperintense signaling of adjacent tissue on both T1- and T2-weighted MRIs. Mycetoma is perhaps the most difficult to differentiate from AFS radiographically. On CTs, mycetomas display increased attenuation, but it is more homogeneous than that of AFS. Also, they usually only involve the maxillary sinus and do not lead to bony remodeling. They show hypointensity on T1-weighted MRIs and signal voids on T2-weighted MRIs but lack the peripheral high signal of the inflamed mucosa.4,7 Mucoceles present as homogeneous opacifications on CTs, hypointense lesions on T1-weighted MRIs, and hyperintense lesions on T2-weighted MRIs. Finally, the neoplastic presentation varies on MRIs but often involves high central signal intensity and more pronounced bony destruction.6 In the present case, AFS was ultimately confirmed by endoscopic sphenoidotomy, which liberated thick, brown secretions consistent with allergic mucin, and by fungal culture of these secretions, which yielded Bipolaris species. Treatment of AFS requires that each factor responsible for disease propagation be addressed. Surgical removal of the fungal mucin that generates the allergic response is therefore critical. All affected mucosa must be removed and the involved sinuses left widely patent for adequate ventilation and to allow sufficient postsurgical access. Multiple medical options have been used after surgery to treat the inflammatory and immunologic mediators of AFS, including corticosteroids, immunotherapy, and antifungal therapy. However, the optimum combination, dosing, and time requirements of these treatments are controversial. Residents and fellows in otolaryngology are invited to submit quiz cases for this section and to write letters to the ARCHIVES commenting on cases presented. Quiz cases should follow the patterns established. See "Instructions for Authors." Material for CLINICAL PROBLEM SOLVING: RADIOLOGY should be mailed to the Editor. Reprints not available from the authors. References 1. Marple BF Allergic fungal rhinosinusitis: current theories and management strategies. Laryngoscope.2001;111:1006-1019.PubMedGoogle Scholar 2. Bent JKuhn F Diagnosis of allergic fungal sinusitis. Otolaryngol Head Neck Surg.1994;111:580-588.PubMedGoogle Scholar 3. Houser SMCorey JP Allergic fungal rhinosinusitis: pathophysiology, epidemiology, and diagnosis. Otolaryngol Clin North Am.2000;33:399-409.PubMedGoogle Scholar 4. Mukherji SKFigueroa REGinsberg LE et al Allergic fungal sinusitis: CT findings. Radiology.1998;207:417-422.PubMedGoogle Scholar 5. deShazo RDO'Brien MChapin K et al Criteria for the diagnosis of sinus mycetoma. J Allergy Clin Immunol.1997;99:475-485.PubMedGoogle Scholar 6. Martin TJSmith TLSmith MMLoehrl TA Evaluation and surgical management of isolated sphenoid sinus disease. Arch Otolaryngol Head Neck Surg.2002;128:1413-1419.PubMedGoogle Scholar 7. Manning SCMerkel MKriesel K et al Computed tomography and magnetic resonance diagnosis of allergic fungal sinusitis. Laryngoscope.1997;107:170-176.PubMedGoogle Scholar http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology - Head & Neck Surgery American Medical Association

Radiology Quiz Case 4—Diagnosis

Archives of Otolaryngology - Head & Neck Surgery , Volume 130 (9) – Sep 1, 2004

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Publisher
American Medical Association
Copyright
Copyright © 2004 American Medical Association. All Rights Reserved.
ISSN
0886-4470
eISSN
1538-361X
DOI
10.1001/archotol.130.9.1126
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Abstract

Diagnosis: Allergic fungal sinusitis (AFS) of the right sphenoidal sinus Allergic fungal sinusitis is generally recognized as a disease that is distinct from other forms of fungal sinusitis. It most commonly presents in adolescents and young adults, with approximately two thirds of patients reporting a history of allergic rhinitis, and half reporting a history of asthma. Clinical presentation varies from subtle nasal obstruction and crusting to extensive polyposis, chronic sinusitis, acute visual loss, proptosis, and facial dysmorphia. The pathogenesis of AFS is unclear, but immunologic and histologic data suggest that it represents an immunologically mediated disorder rather than an infectious entity. Cultures from patients with AFS most commonly yield organisms from the dematiaceous family of fungi, including Bipolaris.1 Bent and Kuhn2 identified 5 common characteristics (ie, type I hypersensitivity, nasal polyposis, characteristic radiographic findings, eosinophilic mucin without invasion, and positive fungal stain) among 15 cases of AFS. The differential diagnosis of fungal sinusitis is generally divided into invasive and noninvasive forms.3 Invasive disease can be acute (fulminant), characterized by invasion of mucosa, submucosa, and blood vessels by fungal hyphae, most commonly of the Mucorales order or Aspergillus. Patients with invasive disease are usually immunocompromised and require radical surgical debridement. Chronic indolent invasive sinusitis results in noncaseating granulomas that lead to regional tissue invasion in immunocompetent hosts.4 Noninvasive disease includes AFS and mycetomas (paranasal sinus fungal balls). The presenting signs and symptoms of mycetomas, which may be similar to those of AFS, include nasal congestion, a history of chronic sinusitis, rhinorrhea, facial pain, and proptosis. Mycetomas more frequently present in only 1 sinus. Also, they show a chronic inflammatory response in mucosa adjacent to fungal elements (with lymphocytes, plasma cells, and mast cells), and allergic mucin is absent.5 Other diseases that mimic isolated sphenoidal fungal sinusitis are mucoceles and neoplasms.6 Allergic fungal sinusitis has been shown to have characteristic radiographic features. The disease is usually unilateral and affects multiple sinuses. Noncontrast CTs frequently reveal scattered central areas of high attenuation within the involved sinuses. Bone windows, however, can be variable, with a homogeneous ground glass appearance, a starry sky pattern of calcium deposits, or an irregular linear pattern of increased attenuation. Postcontrast T1-weighted MRIs show areas of characteristic hypointense signal that correspond with the regions of high attenuation on CTs. The periphery of involved sinuses will show high signal characteristics as a result of inflammation, especially after the administration of gadolinium–pentetic acid contrast. T2-weighted MRIs will reveal a central signal void in affected sinuses and an intense high peripheral signal. With AFS, evidence of remodeling and destruction of bony sinus walls, likely from pressure atrophy, is often visible on both CTs and MRIs.4,7 Computed tomograms and MRIs of our patient revealed many of these features. An axial CT without contrast (Figure 1) showed a large right sphenoidal mass with several hyperattenuated central regions. A postcontrast T1-weighted MRI (Figure 2) showed multiple regions of hypointense signal within the mass, and a T2-weighted MRI (Figure 3) revealed a signal void within the sinus. Both MRIs demonstrated a narrow, hyperintense periphery of inflamed mucosa. Figure 1. View LargeDownload Figure 2. View LargeDownload Figure 3. View LargeDownload Careful review of CTs and MRIs can help to rule out other differential diagnoses. Fulminant invasive fungal sinusitis reveals mucosal inflammation, with enhancement of the dura or orbits, on CTs and MRIs. Indolent invasive disease leads to mucosal inflammation and bone destruction on CTs as well as to hyperintense signaling of adjacent tissue on both T1- and T2-weighted MRIs. Mycetoma is perhaps the most difficult to differentiate from AFS radiographically. On CTs, mycetomas display increased attenuation, but it is more homogeneous than that of AFS. Also, they usually only involve the maxillary sinus and do not lead to bony remodeling. They show hypointensity on T1-weighted MRIs and signal voids on T2-weighted MRIs but lack the peripheral high signal of the inflamed mucosa.4,7 Mucoceles present as homogeneous opacifications on CTs, hypointense lesions on T1-weighted MRIs, and hyperintense lesions on T2-weighted MRIs. Finally, the neoplastic presentation varies on MRIs but often involves high central signal intensity and more pronounced bony destruction.6 In the present case, AFS was ultimately confirmed by endoscopic sphenoidotomy, which liberated thick, brown secretions consistent with allergic mucin, and by fungal culture of these secretions, which yielded Bipolaris species. Treatment of AFS requires that each factor responsible for disease propagation be addressed. Surgical removal of the fungal mucin that generates the allergic response is therefore critical. All affected mucosa must be removed and the involved sinuses left widely patent for adequate ventilation and to allow sufficient postsurgical access. Multiple medical options have been used after surgery to treat the inflammatory and immunologic mediators of AFS, including corticosteroids, immunotherapy, and antifungal therapy. However, the optimum combination, dosing, and time requirements of these treatments are controversial. Residents and fellows in otolaryngology are invited to submit quiz cases for this section and to write letters to the ARCHIVES commenting on cases presented. Quiz cases should follow the patterns established. See "Instructions for Authors." Material for CLINICAL PROBLEM SOLVING: RADIOLOGY should be mailed to the Editor. Reprints not available from the authors. References 1. Marple BF Allergic fungal rhinosinusitis: current theories and management strategies. Laryngoscope.2001;111:1006-1019.PubMedGoogle Scholar 2. Bent JKuhn F Diagnosis of allergic fungal sinusitis. Otolaryngol Head Neck Surg.1994;111:580-588.PubMedGoogle Scholar 3. Houser SMCorey JP Allergic fungal rhinosinusitis: pathophysiology, epidemiology, and diagnosis. Otolaryngol Clin North Am.2000;33:399-409.PubMedGoogle Scholar 4. Mukherji SKFigueroa REGinsberg LE et al Allergic fungal sinusitis: CT findings. Radiology.1998;207:417-422.PubMedGoogle Scholar 5. deShazo RDO'Brien MChapin K et al Criteria for the diagnosis of sinus mycetoma. J Allergy Clin Immunol.1997;99:475-485.PubMedGoogle Scholar 6. Martin TJSmith TLSmith MMLoehrl TA Evaluation and surgical management of isolated sphenoid sinus disease. Arch Otolaryngol Head Neck Surg.2002;128:1413-1419.PubMedGoogle Scholar 7. Manning SCMerkel MKriesel K et al Computed tomography and magnetic resonance diagnosis of allergic fungal sinusitis. Laryngoscope.1997;107:170-176.PubMedGoogle Scholar

Journal

Archives of Otolaryngology - Head & Neck SurgeryAmerican Medical Association

Published: Sep 1, 2004

Keywords: diagnostic radiologic examination,radiology specialty,fungal sinusitis

References