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Radiology Quiz Case 1: Diagnosis

Radiology Quiz Case 1: Diagnosis Diagnosis: Extracranial meningioma Tumors of the parapharyngeal space are often encountered in the suprahyoid neck. The most common tumors in this space are pleomorphic adenomas, tumors of neurogenic origin, and paragangliomas, and they usually do not pose a diagnostic dilemma. Therefore, tissue diagnosis is seldom required. However, certain rare varieties of tumors of the parapharyngeal space may represent a diagnostic challenge and thus may hinder surgical planning. Conventionally, the parapharyngeal space is divided into prestyloid and poststyloid compartments. The tumors that are found in the prestyloid compartment are pleomorphic adenomas, which arise in the deep lobe of the parotid gland or in the salivary gland rests and displace the carotid sheath posteriorly. Paragangliomas and neurogenic tumors arise in the poststyloid compartment. Paragangliomas displace the carotid sheath anteriorly, and MRI may demonstrate typical flow voids or a “salt-and-pepper” appearance on T2-weighted sequences, with striking early postcontrast enhancement on dynamic CT scans or MRIs. Glomus tumors may also produce permeative lytic erosions in the region of the jugular foramen. Neurogenic tumors (schwannomas or neurofibromas) are homogeneously hyperintense on T2-weighted images when they are small and may show necrotic areas when they are large. The ICA is displaced anteriorly, and the internal jugular vein is displaced posterolaterally. Neurogenic tumors display slightly delayed but good contrast enhancement. Calcification is rarely encountered in these tumors, although intracranial extension may occur in cases involving large tumors. Jugular schwannomas may cause scalloped erosion of the jugular foramen. In the present case, dense calcification was evident within the tumor, which was located in the poststyloid compartment. Striking enhancement was absent. Low signal intensity was seen in the central regions on T2-weighted images. The ICA and the internal jugular vein were dispaced anteriorly and encased as well. These imaging features were not typical of paragangliomas or schwannomas. Although papillary thyroid carcinoma is a histologic differential diagnosis in this case, metastasis of thyroid cancer to the parapharyngeal space is extremely rare. Therefore, an “anatomical” differential diagnosis in this location is very unusual. Furthermore, the gross extensive calcifications in this case also argue against the diagnosis of metastatic thyroid cancer, unlike nodal metastases from thyroid cancers, which usually display punctate calcification. Extracranial meningiomas, which represent up to 2% of meningiomas, are seen rarely in the parapharyngeal space. They can be divided into the following 4 groups1: (1) primary intracranial meningiomas that extend directly from the skull; (2) extracranial meningiomas that arise from arachnoid cell rests of cranial nerve sheaths; (3) meningiomas that have no demonstrable connection with the foramina or cranial nerve; and (4) metastases of malignant intracranial meningiomas. These tumors are difficult to diagnose both by imaging and by cytologic examination. Although the cytologic features of meningiomas are well known, extracranial meningiomas can masquerade as a wide variety of histologic differential diagnoses in the parapharyngeal space. According to Tan,2there are several factors that make the differentiation of these tumors so difficult, such as the low frequency of their occurrence in the head and neck region, the complexity involved in distinguishing the cytomorphological features of tumors involving the meningoepithelium from other epithelium, the nondistinct nature of menigothelial cells, and the largely noncontributory nature of cytologic nuances. Also, cytomorphological features such as round cell clusters, psammoma bodies, nuclear grooves, and intranuclear inclusions may overlap with those of more commonly aspirated head and neck tumors, such as acinic cell carcinoma, metastatic papillary thyroid carcinoma, and paragangliomas,2thereby posing a frequent diagnostic dilemma in the cytologic diagnosis of extracranial meningiomas. The immunohistochemical antigenic profile of meningiomas includes reactivity with epithelial membrane antigen and vimentin. In contrast to paragangliomas, meningiomas are nonreactive with neuroendocrine markers (eg, chromogranin and synaptophysin).3Therefore, immunohistochemical analysis, though seldom necessary, could be a valuable tool in cases that require additional diagnostic scrutiny. The typical CT features of extracranial meningiomas include florid hyperostosis of the jugular foramen or adjacent bone, calcification within the tumor, and intense enhancement.4The jugular foramen shows smooth expansion. The tumors are hyperintense on T2-weighted images, but low signal intensity may be seen if calcification is present. An associated dural tail may be present in the skull base, extending into the posterior fossa. The presence of calcification and the dural tail in this case, with smooth expansion of the jugular foramen, favored a diagnosis of meningioma over paraganglioma or schwannoma. The findings of a biopsy, which was performed because of the discrepancy in the cytologic and radiologic diagnosis, confirmed the diagnosis of meningothelial meningioma. The behavior of extracranial meningiomas is different from that of other tumors in the parapharyngeal space, with meningiomas having a much higher likelihood of recurrence after resection. Furthermore, meningiomas tend to have worse postoperative outcomes than paragangliomas or schwannomas.5Therefore, preoperative confirmation of the results of histologic analysis may be crucial to surgical planning and preoperative counsel. In conclusion, the possibility of rare tumors of the parapharyngeal space should be kept in mind, especially when there is disagreement between the cytologic and radiologic features in diagnosis. The presence of tumor calcification with intracranial extension and a dural component should strongly suggest a diagnosis of extracranial meningioma. These findings not only help in making an accurate preoperative diagnosis but also enhance surgical planning, selection of surgical approach, and patient counseling. Return to Quiz Case 1. References 1. Friedman CDCostantino PDTeitelbaum BBerktold RESisson GA Sr Primary extracranial meningiomas of the head and neck. Laryngoscope 1990;100 (1) 41- 48PubMedGoogle Scholar 2. Tan LH Meningioma presenting as a parapharyngeal tumor: report of a case with fine needle aspiration cytology. Acta Cytol 2001;45 (6) 1053- 1059PubMedGoogle ScholarCrossref 3. Thompson LDRGyure KA Extracranial sinonasal tract meningiomas: a clinicopathologic study of 30 cases with a review of the literature. Am J Surg Pathol 2000;24 (5) 640- 650PubMedGoogle ScholarCrossref 4. Shetty CAvinash KRAuluck AMupparapu M Extracranial meningioma of the parapharyngeal space: report of a case and review of the literature. Dentomaxillofac Radiol 2007;36 (2) 117- 120PubMedGoogle ScholarCrossref 5. Lustig LRJackler RK The variable relationship between the lower cranial nerves and jugular foramen tumors: implications for neural preservation. Am J Otol 1996;17 (4) 658- 668PubMedGoogle Scholar http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology - Head & Neck Surgery American Medical Association

Radiology Quiz Case 1: Diagnosis

Archives of Otolaryngology - Head & Neck Surgery , Volume 135 (10) – Oct 1, 2009
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Publisher
American Medical Association
Copyright
Copyright © 2009 American Medical Association. All Rights Reserved.
ISSN
0886-4470
eISSN
1538-361X
DOI
10.1001/archoto.2009.127-b
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Abstract

Diagnosis: Extracranial meningioma Tumors of the parapharyngeal space are often encountered in the suprahyoid neck. The most common tumors in this space are pleomorphic adenomas, tumors of neurogenic origin, and paragangliomas, and they usually do not pose a diagnostic dilemma. Therefore, tissue diagnosis is seldom required. However, certain rare varieties of tumors of the parapharyngeal space may represent a diagnostic challenge and thus may hinder surgical planning. Conventionally, the parapharyngeal space is divided into prestyloid and poststyloid compartments. The tumors that are found in the prestyloid compartment are pleomorphic adenomas, which arise in the deep lobe of the parotid gland or in the salivary gland rests and displace the carotid sheath posteriorly. Paragangliomas and neurogenic tumors arise in the poststyloid compartment. Paragangliomas displace the carotid sheath anteriorly, and MRI may demonstrate typical flow voids or a “salt-and-pepper” appearance on T2-weighted sequences, with striking early postcontrast enhancement on dynamic CT scans or MRIs. Glomus tumors may also produce permeative lytic erosions in the region of the jugular foramen. Neurogenic tumors (schwannomas or neurofibromas) are homogeneously hyperintense on T2-weighted images when they are small and may show necrotic areas when they are large. The ICA is displaced anteriorly, and the internal jugular vein is displaced posterolaterally. Neurogenic tumors display slightly delayed but good contrast enhancement. Calcification is rarely encountered in these tumors, although intracranial extension may occur in cases involving large tumors. Jugular schwannomas may cause scalloped erosion of the jugular foramen. In the present case, dense calcification was evident within the tumor, which was located in the poststyloid compartment. Striking enhancement was absent. Low signal intensity was seen in the central regions on T2-weighted images. The ICA and the internal jugular vein were dispaced anteriorly and encased as well. These imaging features were not typical of paragangliomas or schwannomas. Although papillary thyroid carcinoma is a histologic differential diagnosis in this case, metastasis of thyroid cancer to the parapharyngeal space is extremely rare. Therefore, an “anatomical” differential diagnosis in this location is very unusual. Furthermore, the gross extensive calcifications in this case also argue against the diagnosis of metastatic thyroid cancer, unlike nodal metastases from thyroid cancers, which usually display punctate calcification. Extracranial meningiomas, which represent up to 2% of meningiomas, are seen rarely in the parapharyngeal space. They can be divided into the following 4 groups1: (1) primary intracranial meningiomas that extend directly from the skull; (2) extracranial meningiomas that arise from arachnoid cell rests of cranial nerve sheaths; (3) meningiomas that have no demonstrable connection with the foramina or cranial nerve; and (4) metastases of malignant intracranial meningiomas. These tumors are difficult to diagnose both by imaging and by cytologic examination. Although the cytologic features of meningiomas are well known, extracranial meningiomas can masquerade as a wide variety of histologic differential diagnoses in the parapharyngeal space. According to Tan,2there are several factors that make the differentiation of these tumors so difficult, such as the low frequency of their occurrence in the head and neck region, the complexity involved in distinguishing the cytomorphological features of tumors involving the meningoepithelium from other epithelium, the nondistinct nature of menigothelial cells, and the largely noncontributory nature of cytologic nuances. Also, cytomorphological features such as round cell clusters, psammoma bodies, nuclear grooves, and intranuclear inclusions may overlap with those of more commonly aspirated head and neck tumors, such as acinic cell carcinoma, metastatic papillary thyroid carcinoma, and paragangliomas,2thereby posing a frequent diagnostic dilemma in the cytologic diagnosis of extracranial meningiomas. The immunohistochemical antigenic profile of meningiomas includes reactivity with epithelial membrane antigen and vimentin. In contrast to paragangliomas, meningiomas are nonreactive with neuroendocrine markers (eg, chromogranin and synaptophysin).3Therefore, immunohistochemical analysis, though seldom necessary, could be a valuable tool in cases that require additional diagnostic scrutiny. The typical CT features of extracranial meningiomas include florid hyperostosis of the jugular foramen or adjacent bone, calcification within the tumor, and intense enhancement.4The jugular foramen shows smooth expansion. The tumors are hyperintense on T2-weighted images, but low signal intensity may be seen if calcification is present. An associated dural tail may be present in the skull base, extending into the posterior fossa. The presence of calcification and the dural tail in this case, with smooth expansion of the jugular foramen, favored a diagnosis of meningioma over paraganglioma or schwannoma. The findings of a biopsy, which was performed because of the discrepancy in the cytologic and radiologic diagnosis, confirmed the diagnosis of meningothelial meningioma. The behavior of extracranial meningiomas is different from that of other tumors in the parapharyngeal space, with meningiomas having a much higher likelihood of recurrence after resection. Furthermore, meningiomas tend to have worse postoperative outcomes than paragangliomas or schwannomas.5Therefore, preoperative confirmation of the results of histologic analysis may be crucial to surgical planning and preoperative counsel. In conclusion, the possibility of rare tumors of the parapharyngeal space should be kept in mind, especially when there is disagreement between the cytologic and radiologic features in diagnosis. The presence of tumor calcification with intracranial extension and a dural component should strongly suggest a diagnosis of extracranial meningioma. These findings not only help in making an accurate preoperative diagnosis but also enhance surgical planning, selection of surgical approach, and patient counseling. Return to Quiz Case 1. References 1. Friedman CDCostantino PDTeitelbaum BBerktold RESisson GA Sr Primary extracranial meningiomas of the head and neck. Laryngoscope 1990;100 (1) 41- 48PubMedGoogle Scholar 2. Tan LH Meningioma presenting as a parapharyngeal tumor: report of a case with fine needle aspiration cytology. Acta Cytol 2001;45 (6) 1053- 1059PubMedGoogle ScholarCrossref 3. Thompson LDRGyure KA Extracranial sinonasal tract meningiomas: a clinicopathologic study of 30 cases with a review of the literature. Am J Surg Pathol 2000;24 (5) 640- 650PubMedGoogle ScholarCrossref 4. Shetty CAvinash KRAuluck AMupparapu M Extracranial meningioma of the parapharyngeal space: report of a case and review of the literature. Dentomaxillofac Radiol 2007;36 (2) 117- 120PubMedGoogle ScholarCrossref 5. Lustig LRJackler RK The variable relationship between the lower cranial nerves and jugular foramen tumors: implications for neural preservation. Am J Otol 1996;17 (4) 658- 668PubMedGoogle Scholar

Journal

Archives of Otolaryngology - Head & Neck Surgery – American Medical Association

Published: Oct 1, 2009

Keywords: radiology specialty,meningioma,paraganglioma,neoplasms

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