Posterior interosseous nerve palsy caused by parosteal lipoma of proximal radius

Lipomas are common benign soft tissue tumors which tend to be indolent, and symptoms caused by nerve compression are unusual. However, a parosteal lipoma, occurring adjacent to the proximal radius may easily cause paralysis of the posterior interosseous nerve because of a specific anatomical relationship of these structures in that area. Two cases of parosteal lipoma of the proximal radius causing paralysis of the posterior interosseous nerve are reported. CT and MR imaging demonstrate the characteristic fatty mass around the radius and are specific in making the diagnosis. Surgical excision should be promptly performed to ensure optimal recovery from the nerve paralysis.     

Interhemispheric lipoma connected to subcutaneous lipoma via lipomatous stalk

Lipomas are rare intracranial lesions and are generally thought to be asymptomatic. The vast majority of intracranial lipomas are viewed as incidental findings on imaging studies and treated conservatively. Intracranial lipomas are frequently accompanied by additional intracranial congenital malformations, but only rarely has an association with subcutaneous lipomas been described. We report an infant with a subgaleal lipoma in the region of the anterior fontanelle connected to a large interhemispheric (pericallosal) lipoma via a tiny lipomatous stalk. Because of this association, infants who present with a subcutaneous lipoma of the scalp might be considered for MR imaging to evaluate for an intracranial component.     

Occipital extra- and intracranial lipoencephalocele associated with tectocerebellar dysraphia

Objects Tectocerebellar dysraphism was first described by Padget and Lindenberg, together with occipital encephaloceles, cerebellar midline defects, tectal beaking, posterior kinked and displaced brainstem, and inverted cerebellum. We present a unique case of lipoencephalocele associated with tectocerebellar dysraphia and discuss the etiologies of both pathologies. The importance of the developmental comprehension of posterior fossa malformations is stressed.Case report A 9-month-old girl in good health was referred for a huge occipital mass. On local examination, the patient had a rounded mass about 10×12 cm in size, covered by alopecic skin, with a small eccentric dimple without any discharge. Magnetic resonance imaging revealed a lipoencephalocele with an intra- and an extracranial part, associated with tectocerebellar dysraphia with no aspect of inverted cerebellum as originally described in the tectocerebellar dysraphia. Resection of the extracranial part of the lipoma was performed for esthetic reasons. The intracranial part remained in situ.Conclusion The association of lipoencephalocele and tectocerebellar dysraphia is extremely rare. The functional prognosis seems to be less severe for this combination than for the isolated tectocerebellar dysraphia. This association favors the dysraphic theory for the embryogenesis of the lipoma. It seems safe to restrict the surgery of this bizarre malformation to its external part.Commentaries on this paper are available at , , , , and     

Chondroid lipoma of the trunk: MRI appearance and pathologic correlation

Chondroid lipoma is a rare tumour of adipose tissue, bearing a strikingly close pathologic resemblance to myxoid liposarcoma and extraskeletal myxoid chondrosarcoma. Unlike these malignant tumours, chondroid lipoma has a non-aggressive behaviour and does not require radical treatment. Although repeatedly reported in the proximal extremities and limb girdles, this rare entity may less frequently be observed in the trunk. We describe the imaging findings of a chondroid lipoma in the trunk and provide a discussion on the radiologic-pathologic correlation and differential diagnosis.     

Clustering of deletions on chromosome 13 in benign and low-malignant lipomatous tumors

Deletions and structural rearrangements of the long arm of chromosome 13 are frequently observed in benign and low-malignant lipomatous tumors, but nothing is known about their molecular genetic consequences. We assessed the karyotypes of 40 new and 22 previously published cases (35 ordinary lipomas, 15 spindle cell/pleomorphic lipomas, 2 myxolipomas, 1 angiomyxolipoma and 9 atypical lipomatous tumors) with chromosome 13-abnormalities, and found bands 13q12-22 to be frequently affected. Twenty-seven cases with structural abnormalities within this region were selected for breakpoint and deletion mapping by metaphase fluorescence in situ hybridization (FISH), using a set of 20 probes. Deletions were found in 23 of 27 cases. The remaining 4 cases had seemingly balanced rearrangements. The breakpoints were scattered but clustered to band 13q14, and in all cases with unbalanced abnormalities, a limited region within band 13q14 was partially or completely deleted. A deletion within band 13q14 was found together with a breakpoint on the other homologue in 5 cases, 4 of which could be tested further with regard to the status of the retinoblastoma (RB1)-gene. In all 4 cases, only 1 copy of the gene was deleted. In addition to the breaks and deletions in the vicinity of the RB1-locus, several other regions of 13q were recurrently affected, e.g., in the vicinity of the hereditary breast cancer (BRCA2; 13q12)- and lipoma HMGIC fusion partner (LHFP; 13q13)- genes. Our findings strongly indicate that deletion of a limited region (approximately 2.5 Mbp) within 13q14, distal to the RB1-locus, is of importance in the development of a subset of lipomatous tumors.     

Isolated intraosseous gout in hallux sesamoid mimicking a bone tumor in a teenaged patient

We are reporting an unusual case of isolated intraosseous tophus in medial hallux sesamoid presenting as tumor-like lesion in a teenage patient without prior history of gouty attack and underlying systemic disorders. The lesion manifested isointensity to surrounding muscles with internal low signal on spin echo (SE) T1-weighted images, and heterogeneous low signal intensity on fast spin echo (FSE) T2-weighted images. Computed tomography (CT) scan disclosed expansion and diffusely increased attenuation of the medial hallux sesamoid with focal cortical erosion and extraosseous extension of high attenuation content. The subsequent resection and pathology revealed intraosseous tophus deposition, which is particularly rare at this site and at this age. Imaging studies revealed some characteristic imaging features which can retrospectively be attributed to gouty tophus. When an expansile osteolytic lesion manifesting low signal intensity on T2-weighted image and internal calcifications on CT scan is encountered, the possibility of intraosseous tophus should be included in the list of differential diagnoses, even in a teenage patient without prior history of gout.     

Effects of variation in systemic blood pressure on intraosseous pressure, PO2, and PCO2

Several regulatory mechanisms have been shown to influence the intraosseous circulation. The influence of general hypovolemia on bone circulation and possible regulatory effects were investigated by recording the intraosseous pressure and PO2 and PCO2 continuously by mass spectrometry in rabbits. Hypovolemia was induced by repeated bleedings. The intraosseous and arterial pressures were found to be linearly related. The intraosseous PO2 already decreased after the first step of bleeding and decreased more than 50% of the initial value after an average blood loss of 40 ml. The intraosseous PCO2 showed an opposite pattern. The experimental PO2 vs. arterial pressure curves were similar to curves obtained by a computer simulation that assumes the blood flow to be proportional to the intraosseous pressure.     

Sclerotic lipoma: lipomas simulating sclerotic fibroma

Aims: We report a series of five unusual subcutaneous lipomas characterized by prominent stromal sclerosis in a storiform arrangement. Methods and results: All lesions occurred in young male adults (23.0 ± 9.5 years), three lesions were on the scalp and two on the hands. Clinically, lipoma, chondroma or some form of cyst were suspected. In contrast to sclerotic fibroma (‘circumscribed storiform collagenoma’) a variable number of adipocytes were interspersed within the fibrosclerotic background. These cells also showed immunoreactivity for S100 protein as well as intracytoplasmic lipid deposits ultrastructurally. None of the lesions recurred within a follow-up period of between 0.5 and 9 years. Conclusions: Our series suggests that sclerotic lipomas should be classified with fibro- and myxolipomas, angiolipomas, spindle cell and pleomorphic lipomas, as an additional characteristic subtype of lipoma. Sclerotic lipomas are often misdiagnosed as a sclerotic fibroma, but are essentially fatty tumours and are, at least in our small series, not associated with Cowden's disease.     

A case of atypical inter-muscular lipoma (Evans).

A case of a 51-year-old woman with a lipoma-like tumor on the right arm which showed rapid recurrence after the first simple excision is reported. On the second surgical operation, a lipoma-like tumor with extensive growth between the biceps muscle and brachialis muscle of the right arm was noted. Histological examination revealed almost mature fat cells and scattered atypical lipoblast-like cells. For the treatment of an atypical inter-muscular lipoma, complete excision is necessary, although very extensive treatment is not recommended.     

Lumbosacral lipoma causing tethering of the conus: Case report

We report a case of tethered cord syndrome treated surgically. As in many reported cases, the treatment was successful on pain but only partially so on sphincter dysfunction. The most important diagnostic investigation is CT scanning with contrast medium.

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Sommario Viene riportato un caso con sindrome da tethered cord trattato chirurgicamete. Come in molti dei casi riportati il trattamento ha avuto successo per il dolore, ma solo parzialmente per le disfunzioni sfinteriche. La più importante indagine diagnostica è la CT dopo somministrazione intradurale di mezzo di contrasto.