Protuberant Fibro-osseous Lesions of the Temporal Bone: Two Additional Case Reports

Fibrous and Fibro-Osseous Lesions of Bone

Fibrous and fibro-osseous tumors are some of the most common benign lesions involving bones. Although many of the histomorphologic features of these tumors overlap significantly, an interdisciplinary approach helps to consolidate the classification of these tumors. Herein, the clinical, radiologic, and pathologic features of lesions within these categories are described.

Protuberant Fibro-Osseous Lesion of the Temporal Bone: "Bullough Bump"-Multimodality Imaging Case Series and Literature Review

A handful of cases of protuberant fibro-osseous lesions of the temporal bones have been described in the literature to date, with primary focus on the pathologic features. Here we review 3 cases of pathology-proved protuberant fibro-osseous lesions of the temporal bone and include a literature review with a focus on the imaging features. While rare, these lesions have near-pathognomonic imaging features defined by a location at the cortex of the outer table of the temporal bone at the occipitomastoid suture, lack of involvement of the underlying marrow, variable mineralization, and MR signal characteristics atypical of a chondroid lesion. One case in this series was FDG-avid and had occasional mitotic features, possibly reflecting an aggressive variant. Neuroradiologists should be familiar with this benign diagnosis to aid in timely identification and avoid unnecessary additional imaging.

Protuberant fibro-osseous lesion of the temporal bone: report of four cases and review of the literature

'Bullough lesions', also referred to as protuberant fibro-osseous lesions (PFOL), are rare temporal bone lesions initially described in 1999. Since only 12 cases have been reported, several key issues, such as their origin and recommended management strategies, remain unresolved. This article reports the largest cohort included in the literature to date, comprising four patients with PFOL. PFOL appears to be characterized by female and right-side predominance. These lesions were consistently located regarding the mastoid, generally diagnosed in early adulthood, without functional symptoms, and were always fibro-osseous. Invasive/malignant features were not found on imaging or histology. The main differential diagnosis was malignant low-grade parosteal osteosarcoma. Clinical examination and computed tomography images provided strong elements supporting the diagnosis of PFOL. Biopsy allowed molecular biology investigations (MDM2 and CDK4 amplification), in order to rule out low-grade parosteal osteosarcoma.

Synchronous Occurrence of Colloid Cyst With Intracranial Ossifying Fibromyxoid Tumor Masquerading as Meningioma

Ossifying fibromyxoid tumor (OFMT) is a rare fibro-osseous neoplasm. We present a case highlighting the occurrence of an intracranial OFMT masquerading as meningioma on imaging in a 46-year-old gentleman. Brain imaging revealed an extra-axial calcified lesion along the left cerebellar convexity appearing hypointense on T1- and T2-weighted MRI sequences with no post-contrast enhancement, suggestive of a meningioma. An intraventricular colloid cyst was also noted. The lesion, which was presumed to be meningioma, and the colloid cyst were resected in two subsequent operative settings. Histopathological examination of the calcified lesion confirmed the findings of an OFMT. This report aims to inform the physician about intracranial OFMT mimicking meningioma on imaging. In addition, since multiple brain tumors are not very common, the surgeon should always have a suspicion should there be any heterogeneous and peculiar radiological and histopathological characteristics.

Ear and Temporal Bone: Cartilaginous and Osseous Pathologies

Although the majority of conditions involving the ear and temporal bone are inflammatory or epithelial based, cartilage and osseous entities will also be encountered. The pathologic examination of these underlying cartilaginous and osseous structures and their histologic findings and associated differential diagnoses will be discussed. Correlation with clinical and imaging findings are also critical for accurate determination of the pathologic entity.

Bullough's bump: unusual protuberant fibro-osseous tumor of the temporal bone. Case report

Scalp and calvarial masses are common in children and the differential diagnosis is broad. The authors recently cared for a child with an unusual fibro-osseous lesion of the temporal bone that has previously not been described in the pediatric neurosurgery literature. A 10-year-old girl presented with a firm, slowly enlarging protuberant mass arising from the squamous suture of the temporal bone without intracranial extension. The mass was removed en bloc through a temporal craniectomy and cranioplasty was performed. The patient had a smooth postoperative course. Histological examination showed multiple oval osseous islands dispersed throughout a bland fibrous stroma. The pathological diagnosis was "Bullough's bump," a rare, benign fibro-osseous neoplasm first described in 1999, and only 8 reported cases appear in the literature. Here the authors report the first case of Bullough's bump in a child.

Papillary thyroid carcinoma with nodular fasciitis-like stroma and β-catenin mutations should be renamed papillary thyroid carcinoma with desmoid-type fibromatosis

Various histological variants of papillary thyroid carcinoma have been reported, some with clinical implications, some with peculiar, sometimes misleading morphologies. One of these rare and poorly characterized variants is papillary thyroid carcinoma with nodular fasciitis-like stroma, of which fewer than 30 cases have been documented, mostly as isolated reports. It is a dual tumor comprising a malignant epithelial proliferation that harbors typical features of conventional papillary thyroid carcinoma, admixed with a prominent mesenchymal proliferation resembling nodular fasciitis or fibromatosis. Thus, the terms papillary thyroid carcinoma with nodular fasciitis-like stroma and papillary thyroid carcinoma with fibromatosis-like stroma are used interchangeably; however, the former term suggests a self-limited and regressing disease, whereas the latter one suggests a recurrent and potentially aggressive one. Better genetic and ultrastructural characterization could lead to more appropriate terminology and management. We performed detailed clinicopathological and molecular analyses of two cases of PTC with prominent mesenchymal proliferation that developed in the thyroid gland of two male patients aged 34 and 48. In both cases, the epithelial component harbored a heterozygous somatic activating BRAF mutation (p.V600E). Also, in both cases, the mesenchymal component showed typical aberrant nuclear and cytoplasmic immunoreactivity for β-catenin and harbored a heterozygous somatic activating mutation in the corresponding CTNNB1 gene (p.S45P). This mutation has never been reported in thyroid stroma; in other tissues, it is typical of desmoid-type fibromatosis rather than nodular fasciitis-like stroma. We therefore propose that in cases of papillary thyroid carcinoma with a prominent mesenchymal component, mutations in CTNNB1 should be sought; when they are present, the term 'papillary thyroid carcinoma with desmoid-type fibromatosis' should be used. As the mesenchymal component of these tumors is not expected to concentrate radioactive iodine, special considerations apply to clinical evaluation and follow-up, which should be brought to the attention of the treating specialist.

[The nasolabial cyst encountered in the practical work of the otorhinolaryngologists]

Two clinical observations of nasolabial cyst of uni- and bilateral localizations are reported. The comprehensive characteristic of nasolabial cysts is presented with special reference to the principal diagnostic criteria for this pathology and the potential diagnostic errors.