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Unlabelled: OBJECTIVE, DESIGN AND PATIENTS: Hibernoma is an uncommon, slow-growing, benign soft-tissue tumour resembling brown adipose tissue. The histological appearances are well-documented, but there are relatively few descriptions of the magnetic resonance (MR) imaging features. We report a retrospective comparison of the histological and MR appearances of ten hibernomas of the extremities, classified histologically into lipoma-like [<70% multivacuolated adipocytes (MVAs)] and non-lipoma-like hibernomas (>70% MVAs)., Results: The lipoma-like hibernomas measured 4-27 cm in maximum size. All were well-defined on MR imaging and histology except for one subcutaneous lesion that blended in with surrounding fat histologically. All lesions were isointense with subcutaneous fat on T1- and T2-weighting apart from one lesion that was predominantly slightly hypointense on T1-weighting and predominantly slightly hyperintense on T2-weighting and STIR. Two slightly inhomogeneous lesions contained thin (<5 mm thickness) tortuous vessels. One patient received intravenous contrast, but the lesion did not enhance. The six non-lipoma-like hibernomas measured 2.5-15.5 cm in maximum size and all were unencapsulated. Three were well-defined and three partly ill-defined on MR imaging. There were no significant differences in the MR characteristics of the non-lipoma-like variants. On T1-weighting, the non-lipoma-like hibernomas that contained >90% MVAs were predominantly slightly hypointense to subcutaneous fat. One lesion was isointense with subcutaneous fat, but this lesion only contained from 80-90% MVAs. All non-lipoma-like lesions were slightly hyperintense on STIR but so too were two of the four lipoma-like lesions. Four of the six non-lipoma-like lesions showed marked or moderate inhomogeneity due to thick septa and prominent vessels. Of the two cases that received intravenous contrast, both showed enhancement corresponding to regions of >90% MVAs or prominent vessels within fibrous septa., Conclusions: MR imaging has shown some distinguishing features between lipoma-like and non-lipoma-like hibernomas. Lipoma-like hibernomas are usually isointense with subcutaneous fat on T1-weighting, are either homogeneous or slightly inhomogeneous and may contain thin tortuous vascular structures. Non-lipoma-like hibernomas are pre-dominantly slightly hypointense to subcutaneous fat on T1-weighting, often display marked or moderate inhomogeneity with prominent septa and vessels and enhancement is typical. The appearances of non-lipoma-like hibernomas are not diagnostic and may be mimicked by lipoma variants and by well-differentiated liposarcoma or atypical lipoma.

A 15-year-old male presented with an 18-month history of increasing swelling on the radial aspect of his left forearm. Radiographs and MR images showed a partly calcified mass on the lateral border of the radius with erosion of the underlying cortex. Following a CT-guided needle biopsy, the mass was excised by segmental resection of the radial shaft with replacement by a vascularised fibular graft. Histological examination of the resected specimen showed many features typical of a bizarre parosteal osteochondromatous proliferation (BPOP) but with destruction of the underlying cortical bone by cellular spindle cell tissue. Although there were no cytological signs of malignancy, we believe that this unusual disease should be regarded as a particularly aggressive form of BPOP and treated by wide excision. Clinical follow-up of our patient at 2 years shows no sign of local recurrence or metastasis.

Enlargement of the peroneus longus muscle is a common occurrence in patients with forefoot pes cavus, and may contribute to the cavus deformity. The present study compares the morphology of up to five lower leg muscles from 17 patients with forefoot pes cavus with those of normal muscles. Eight cases had an identifiable neurogenic cause for the cavus. In four cases of hereditary motor-sensory neuropathy, the tibialis anterior showed more severe damage than the peroneus longus. In two cases of cerebral palsy, fibre atrophy and increased oxidative enzyme activity were observed. In nine clinically idiopathic cases, the histological appearances ranged from normal to generalised fibre atrophy or hypertrophy in individual muscles. There was a trend for the mean fibre area to be greater in peroneus longus than in tibialis anterior in six of the idiopathic group of patients. The muscle cross-sectional area on magnetic resonance imaging was correlated closely with the mean fibre area measured on tissue sections. In idiopathic forefoot pes cavus, fibre hypertrophy in peroneus longus (relative to tibialis anterior) may contribute to the cavus deformity. Muscle fibre hyperplasia may contribute to the peroneal muscle enlargement in Friedreich's ataxia. In none of the cases was peroneus longus enlargement due to fat or fibrous tissue replacement.

We report two cases of chemodectoma of the larynx. A 70-year-old man underwent a laryngectomy in April 1984 for a tumor diagnosed as a squamous cell carcinoma but which postoperatively proved to be a chemodectoma. Ipsilateral cervical metastases appeared 2 years later and were removed by local excision. Shortly thereafter he presented with recurrent nodes in both sides of the neck as well as cutaneous metastases on the trunk. He was given chemotherapy using a DTIC regime (5-3,3-dimethyl-1-triazino imidazole-4-carboxamide). A 53-year-old lady underwent a total laryngectomy in May 1984 for an extensive chemodectoma of the larynx. The tumor had already invaded the trachea and thyroid gland. Distant metastases were not found. So far she is free of recurrence. We discuss the histology, site, clinical course and therapy of this extremely rare tumor.

Head and neck surgery may be complicated by penetration of the dura resulting in meningitis, cerebrospinal rhinorrhoea, cerebral abscess or other intracranial complications. The strength of the dura mater both protects the brain and spinal cord and makes dura an ideal material for grafting (when needed). This study examines the thickness and histological composition of dura mater at various sites encountered in head and neck surgery. Dura was removed from eight specified locations in 14 adult cadavers. Microscopically, this dura was found to consist predominantly of collagen fibres, although the thickness of the dura varied between sites. Dura was significantly thinner in relation to the ethmoid sinus (P less than 0.01), tegmen (P less than 0.05) and sigmoid sinus (P less than 0.001), indicating its greater susceptibility to possible injury at these sites during surgery. The variety of its thickness also makes dura a more versatile homograft material than hitherto realised.