No abstract

Findings on MRI remain key in guiding the diagnosis of pituitary stalk lesions, particularly when used in conjunction with other clinical clues. There are no good imaging predictors for hypopituitarism, making clinical evaluation of all patients with pituitary stalk lesions crucial.

Ring-enhancing lesions seen on MR images can occur with a variety of etiologies. Some ring-enhancing lesions have hypointense rims peripherally on T2-weighted MR images. In this study, we examined whether T2 hypointense rims were associated with specific pathologies. A search for ring-enhancing lesions on MR images obtained from 1996 to 2004 was performed, and revealed 221 patients with MRI findings of ring enhancement. The pattern of T2 hypointensity (arc or rim) corresponding with ring enhancement was recorded. In addition, we analyzed other imaging characteristics, including signal on diffusion-weighted images, central homogeneity on T2 and multiplicity of lesions. We then reviewed clinical data on the patients to ascertain the diagnosis for each examination. The most common associated pathologies in our study were gliomas (40%), metastases (30%), abscesses (8%) and multiple sclerosis (MS; 6%). Hypointense borders on T2-weighted images were present in 67% of lesions in the form of a rim in 40% and an arc in 60%. Abscesses had the highest percentage of hypointense rims. Metastases and gliomas more commonly had arcs, and MS lesions were divided between rims and arcs. Abscesses and MS lesions were more commonly homogeneous centrally, compared to gliomas and metastases. Additionally, abscesses were more often bright on diffusion imaging than the other pathologies. As expected, abscesses and MS lesions were usually multiple, whereas metastases were typically multiple in approximately 50% of the patients; gliomas were generally solitary. Trends in T2 hypointensity may aid in distinguishing among etiologies of ring-enhancing lesions, although there is overlap between the MR appearance of these various pathologies.

Little is known about the long-term outcome of patients with thyroid dermopathy, an extrathyroidal manifestation of Graves' disease. Also, it is not known to what degree treatment promotes remission of the lesions. The present report supplies information on the natural course of mild, untreated and severe, treated thyroid dermopathy. In this study, we report on the outcomes of 178 patients seen at our institution between January 1969 and November 1995 with thyroid dermopathy who were followed up for an average of 7.9 yr. Nonpitting edema was the most prevalent form of dermopathy (43.3%), and the pretibial area was the region most commonly involved (99.4%). The majority of patients with dermopathy had ophthalmopathy (97.0%). Topical corticosteroids were the most commonly used treatment (53.9%). Patients with milder forms of dermopathy (40.4%) did not receive any therapy for dermopathy. Twenty-six percent of the patients experienced complete remission, 24.2% had moderate improvement (partial remission), and 50.0% had no or minimal improvement of their dermopathy at last follow-up. Patients who did not receive therapy experienced a significantly (P = 0.03) higher rate of complete remission (34.7%) than those who received local therapy (18.7%), although the combined complete and partial remission rates were not significantly different for the treated and untreated groups (P = 0.3). However, the treated and untreated groups were not comparable because our practice is to use therapy for more extensive and severe cases. All five cases of elephantiasis were in the treatment group and were less likely to have remission because of the severity of their skin condition. Patients receiving treatment were more likely to have dermatologic consultation and histologic diagnosis (P < 0.001). The beneficial effect of topical corticosteroid therapy on long-term remission rates remains to be determined.

SUMMARY: DWI is a useful technique for the evaluation of cholesteatomas. It can be used to detect them when the physical examination is difficult and CT findings are equivocal, and it is especially useful in the evaluation of recurrent cholesteatoma. Initial DWI techniques only detected larger cholesteatomas, Ͼ5 mm, due to limitations of section thickness and prominent skull base artifacts. Newer techniques allow detection of smaller lesions and may be sufficient to replace second-look surgery in patients with prior cholesteatoma resection.ABBREVIATIONS: ASSET ϭ array spatial sensitivity encoding technique; DWI ϭ diffusion-weighted imaging; EPI ϭ echo-planar imaging; HASTE ϭ half-Fourier acquired single-shot turbo spin-echo; PROPELLER ϭ periodically rotated overlapping parallel lines with enhanced reconstruction; SNR ϭ signal intensity-to-noise ratio; SS TSE ϭ single-shot TSE; TSE ϭ turbo spin-echo C holesteatomas are enlarging collections of keratin within a sac of squamous epithelium and may be congenital or acquired.1 Acquired cholesteatomas generally occur in the middle ear and mastoid, whereas congenital cholesteatomas or epidermoids can occur in other locations, including the cerebellopontine angle, suprasellar cistern, calvarium, and multiple sites in the temporal bone. Congenital cholesteatomas compose only 2% of middle ear cholesteatomas. 2There are multiple theories regarding cholesteatoma development, but most authors believe there is a disruption of the normal process in which skin lining the tympanic membrane migrates externally within the external auditory canal. Retraction pockets, which are invaginations of the tympanic membrane into the middle ear cavity, develop and interfere with this process. These pockets are largely due to chronic otitis media and eustachian tube dysfunction, which can cause negative middle ear pressure. Retraction pockets occur most commonly in the pars flaccida of the membrane and less commonly in the pars tensa. Epithelial ingrowth may occur as a result of this process, and squamous debris can become trapped within these retraction pockets in the middle ear space.1,3 Many authors also believe that there is a hereditary predisposition to the development of acquired cholesteatomas. 2Complications of cholesteatomas are related to bony erosion. Erosion is generally thought to be related to mechanical pressure, though some believe that adjacent granulation tissue, an osteoclast stimulator, or collagenase production is necessary.1,2 Bony erosion can result in destruction of the ossicles, creating conductive hearing loss, labyrinthine fistulas with sensorineural hearing loss and vertigo, facial nerve canal erosion and facial paralysis, and rare intracranial complications, such as meningitis and abscess. 1,2The treatment for middle ear cholesteatomas is surgical excision. Small cholesteatomas limited to the Prussak space without significant bone erosion can often be effectively resected by using a transcanal atticotomy approach with subsequent tympanoplasty. Patients may undergo...