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Temporal bone secretory meningioma presenting as a middle ear mass Cosme Eren˜oa,, Agustı´ n Pe´rez Izquierdob, Jose´ M. Basurkoc, Francisco J. Bilbaoa, Jose´ I. Lo´peza a
Department of Anatomic Pathology, Hospital de Basurto, Avda. de Montevideo 18, Basque Country University, 48013 Bilbao, Spain b Department of Otolaryngology, Hospital de Basurto, Avda. de Montevideo 18, Basque Country University, 48013 Bilbao, Spain c Department of Radiology, Hospital de Basurto, Avda. de Montevideo 18, Basque Country University, 48013 Bilbao, Spain Received 21 September 2005; accepted 23 December 2005
Abstract A 44-year-old woman presented with a history of increasing left hypoacusis and sporadic vertigo. CT scan revealed a tumor occupying the mastoid, middle ear, and external auditory canal. After surgical removal, a typical secretory meningioma was diagnosed. The histological hallmark and the immunohistochemical profile of secretory meningiomas are reviewed. The differential diagnosis of this tumor in this location is also commented on. As far as we know, primary temporal bone meningiomas with secretory histology have not been previously reported in the medical literature. r 2006 Published by Elsevier GmbH. Keywords: Secretory meningioma; Temporal bone meningioma; Extracranial meningioma; Differential diagnosis; Immunohistochemistry
Introduction Meningioma presenting as a temporal bone mass is an infrequent clinical situation. Most of them actually represent the secondary extension of intracranial meningiomas. Genuine extracranial and primary temporal meningiomas are very rare, accounting for less than 1% of total meningiomas [10]. Conventional (meningothelial, psammomatous, fibrous) meningiomas hardly ever cause diagnostic difficulties, because these tumors display distinct and typical histologies. However, rare variants of these tumors in atypical sites may be a diagnostic challenge for the pathologist. Corresponding author. Tel.: +34 94 400 6033; fax: +34 94 400 6302. E-mail address:
[email protected] (C. Eren˜o).
0344-0338/$ - see front matter r 2006 Published by Elsevier GmbH. doi:10.1016/j.prp.2005.12.010
We present a case of secretory meningioma arising in the temporal bone that was clinically presented as a middle ear mass. To the best of our knowledge, this is a clinical condition that has not been published previously.
Clinical history A 44-year-old woman presented with increasing left hypoacusis and occasional vertigo of several months of evolution. CT scan disclosed a tumor involving the mastoid, middle ear, and external auditory canal (Fig. 1). The tumor preserved the bone integrity without disruption of the temporal inner table, and was surgically removed.
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Fig. 2. Typical organoid arrangement of epithelioid cells lying in a fibrous stroma with abundant glandular lumina filled with eosinophilic material (pseudopsammomas) (hematoxylin and eosin, original magnification 250). Inset: Histologic detail showing hyaline secretions and an empty nucleus ( 400).
Fig. 1. CT scan showing a tumor in the left temporal bone.
Materials and methods The surgical resection provided two whitish tumor fragments of 10 and 4 mm in diameter that were obtained from the external auditory canal and from the middle ear, respectively. Tissue fragments were submitted to the Laboratory of Pathology and processed in a routine way. Hematoxylin–eosin, periodic-acid-Schiff (PAS), reticulin, and Masson’s trichrome techniques were performed. Immunohistochemistry with cytokeratins (CK7, CK8/18, CK19, CK20, 34bE12, AE1/AE3), vimentin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), Ki67, progesterone and estrogen receptors, chromogranin, synaptophysin, CD56, actin, S-100 protein, and HMB-45 was performed in an automated DAKO immunostainer at conventional dilutions.
Results Histologically, both fragments showed an organoid tumor arrangement composed of small nests of epithelioid cells lying in a fibrous stroma (Fig. 2). Tumor cells
Fig. 3. Immunohistochemical profile showing positivity for cytokeratins, vimentin, CEA, and EMA in tumor cells (original magnification 400, hematoxylin counterstain).
displayed rounded or ovoid nuclei with a finely distributed chromatin and large eosinophilic cytoplasm. Empty nuclei were occasionally seen. Mitoses and atypia were not detected. A prominent glandular differentiation was evidenced in extensive tumor areas. Central lumina frequently contained spherules of an eosinophilic, PAS-diastase positive material (Fig. 2). Only a detailed search revealed scarce areas with typical meningothelial appearance. Proliferating cells showed intense positive immunostaining with a broad spectrum of cytokeratins (CK7, CK8/18, CK19, 34bE12, AE1/AE3) and vimentin (Fig. 3). EMA and CEA were positive in the lumina and some intraluminal spherules (Fig. 3). Proliferative activity (Ki67) was very low, while progesterone and estrogen receptors were negative. CK20, chromogranin, synaptophysin, CD56, actin, S-100 protein, and HMB45 gave negative results.
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Discussion Secretory meningioma was first described by AlguacilGarcı´ a et al. [1] in 1986, and amounts to less than 3% of meningiomas [8]. Although well recognized from the histologic viewpoint, this variant may mimic other tumors and present some diagnostic difficulties in selected cases. Extracranial meningiomas are exceedingly rare neoplasms. In fact, there are very few examples described in the head and neck region [9] and elsewhere (skin, mediastinum, retroperitoneum, peripheral soft tissue, and lung) [12]. Primary ear and temporal bone meningiomas have recently been reviewed by Thompson et al. [10], who collected 36 new cases, the largest series published so far. These authors stress the difficulties in diagnosing these tumors in this atypical location and state that a wide group of both malignant and benign tumors may be considered in the differential diagnosis [9]. It is noteworthy that none of the tumors in Thompson’s series, nor in their review, was a secretory meningioma, and we have not found in our medical literature search any previously reported case of extracranial meningioma with secretory features. We consider that the sum of a secretory histology and an atypical location can make the diagnosis of meningioma particularly puzzling, especially in the complex temporal bone anatomy in which several infrequent tumors may eventually appear. So, aside from secretory meningioma, other diagnostic possibilities may appear in the pathologist’s mind when faced with a temporal bone neoplasm. For example, a tumor occupying the middle ear, invading the mastoid and external auditory canal, confined to the temporal bone, and displaying an organoid arrangement with large epithelioid cells and with some glandular features may also raise the possibility of a paraganglioma, a middle ear adenoma, the so-called ceruminoma, an adenoid cystic carcinoma (with cribiform pattern), some poorly differentiated adenocarcinomas (primary or metastatic), and a mucoepidermoid carcinoma. The diagnostic hallmark of secretory meningioma is the presence of epithelial differentiation in the proliferating meningothelial cells with intracellular lumina containing eosinophilic and PAS-positive material (known as pseudopsammoma bodies). The immunohistochemical profile is also quite specific, with positive immunostaining with cytokeratins, vimentin, and EMA. Quite typically, pseudopsammoma bodies are CEApositive, while the surrounding tumor cells are cytokeratin-positive [3]. Although some authors stress that temporal meningiomas are uniformly negative for cytokeratins [5], a recent study of a large series of cases confirms the constant expression of simple and stratified cytokeratins in this subtype of meningioma [7]. Paragangliomas also display an organoid pattern, they are more frequently found in women, and may
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occasionally present hyaline intracytoplasmic globules [4,11], but the immunohistochemical profile is distinct and diagnostic. Middle ear adenomas display endocrine differentiation and produce mucicarmin-positive material in the lumina [5]. In addition, ceruminous glandderived tumors in the external auditory canal (ceruminomas, adenoid cystic carcinomas, and well-differentiated adenocarcinomas) [2,6,9] may be considered a diagnostic alternative as well, but most have a typical histology and show myoepithelial differentiation in the basal cells. Mucoepidermoid carcinomas vary in their histologic appearance and may also be included in the differential diagnosis. Some metastatic carcinomas may show hyaline material in the lumina, but atypia and mitoses appear in the context of a true epithelial tumor. In addition, some adenocarcinomas are positive for CK20, and this fact rules out the meningioma. Finally, the negative immunostaining with S-100 protein and HMB45 helps to exclude schwannoma and malignant melanoma. To conclude, meningioma arising in the temporal bone is a rare condition, although the typical meningothelial histology may help in the diagnosis. However, secretory meningioma has never been reported in this location, and the differential diagnosis in routine practice may eventually result in some difficulties. Anyway, the recognition of its histologic characteristics and its distinct immunohistochemical profile are reliable tools in achieving the correct diagnosis.
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