Bizarre parosteal osteochondromatous proliferation (Nora’s lesion): report of two cases

Abstract We describe two cases of bizarre parosteal ostechondromatous proliferation (BPOP), commonly known as Nora’s lesion from the author who first described it, arising from the hands of two middle-aged patients. We emphasize the rarity of this lesion and the difficulty in diagnosis, since the histological pattern may mimic that of a malignant sarcoma.     

Mediastinal lipoma: Report of a case

We experienced a case of mediastinal lipoma, which is considered to be a relatively rare disease. A 3-year-old girl was referred to Gifu University hospital because of fever and an abnormal shadow on her chest X-ray. The chest X-ray clearly showed a well-delineated tumor shadow which seemed to oppress the diaphragm and the right atrium in the right lower lung area. A computed tomogram (CT) of the chest showed a homogeneous mass localized on the right diaphragm and adjoining the right anterior chest wall and heart. The mass showed a fat density measuring about-100 HU. Magnetic resonance imaging (MRI) showed a high-intensity mass which was almost the same level as the subcutaneous fat on both the T₁-weighted and T₂-weighted images. Thoracotomy was performed and a fatty tumor was found. It arose from the right side of the pericardium and adjoined the diaphragm, the anterior chest wall, and the thymus. There was no adhesion between the tumor and the surrounding organs. It was resected easily and its contents were yellowish and homogeneous. The patient made an uneventful recovery and was discharged 10 days after the operation. Light microscopy showed a lipoma consisting of mature adipose tissue and no malignancy was found.     

Sialolipoma of the hard palate

Sialolipoma is a new variant of salivary gland lipoma, which was first proposed by Nagao et al. (Histopathology 2001; 38: 30) in 2001. We report this rare case of sialolipoma in the hard palate. A 60-year-old Japanese woman was referred to our department complaining of a painless swelling on the right side of the hard palate. Intra-oral examination revealed a soft, elastic, dome-shaped mass with 1 cm in diameter located in the posterior part of the hard palate. Magnetic resonance imaging examination revealed high intensity on T(1)-weighted image and isointensity on T(2)-weighted image. Incisional biopsy revealed that the tumor was encapsulated by fibrous tissue, consisted of adipose tissue, and also contained normal salivary gland tissue peripherally. First diagnosed as an ordinary lipoma of the hard palate, the tumor was excised. According to the recent criteria of histologic findings of sialolipoma, we rediagnosed the tumor as sialolipoma of the hard palate.     

Accessory Scrotum with Penoscrotal Transposition and Retrocerebellar Arachnoid Cyst: A Case Report

A 2-year-old boy presented with an accessory scrotum associated with penoscrotal transposition and a perineal lipoma. He also had a retrocerebellar arachnoid cyst. The accessory scrotum was resected with concurrent scrotoplasty. The retrocerebellar arachnoid cyst was seen on a subsequent brain computed tomography scan and was left untreated because there was no evidence that the volume was increasing.     

Parosteal fasciitis of the clavicle

A rare case of parosteal fasciitis arising from the periosteum of the left clavicle in a 27-year-old woman is reported. Magnetic resonance imaging demonstrated the lesion surrounding the periosteum of the clavicle. The lesion was iso-intense with muscle on T(1)-weighted images and hyperintense on T(2)-weighted images. At surgery, the lesion was discovered to be densely adherent with the periosteum, and excised along with the periosteum. Histopathological examination revealed the proliferation of myofibroblasts in a vague storiform or short fascicular pattern. A large amount of extravasated erythrocytes, and a few lymphocytes were present in the matrix. There were some foci of abundant myxoid materials. Immunohistochemical study showed the cells to be positive for vimentin, alpha-smooth muscle actin and HHF35, but negative for desmin. There was no local recurrence at a 6 months postoperative follow up.     

Two unusual benign lesions of the neck masquerading as malignancy on fine-needle aspiration cytology

Two cases of unusual benign tumors of the neck are described, both of which were initially misdiagnosed on cytology as carcinomas. Fine-needle aspiration findings in each case demonstrated a pleomorphic population of cells including bizarre multi-nucleated giant cells, the latter raising the false impression of malignancy. However, on review the cytological appearances of the tumors, a pleomorphic lipoma and a carotid body tumor, were characteristic. the correct diagnosis in each case would have been made or suggested if the pathologist had been familiar with the cytologic features characteristic of the lesion and the differential diagnosis of the head and neck tumors. in addition, the point is made that adequate clinical information is essential for the pathologist if all relevant conditions are not to be missed in the differential diagnosis.     

Angiomyolipoma mimicking true lipoma of the liver: report of two cases

Hepatic angiomyolipoma (AML) is very rare and only about 80 cases have been reported. The tumor is fundamentally heterogeneously composed of the three tissue components of blood vessels, smooth muscle cells (SMC), and fat cells. Two cases of hepatic AML are reported here, both of which are histologically composed predominantly of a fat cell element and resembled true lipoma (lipomatous AML). However, careful examination of both tumors revealed the presence of a small amount of epithelioid SMC, especially around blood vessels. Immunohistochemical study using monoclonal antibody for melanoma (HMB-45) clearly revealed a small amount of HMB-45-positive SMC around the blood vessels and scattered in the diffuse fat cell growth in both tumors. Since no liver tissue components or primary liver tumors are reactive with HMB-45 except AML cells, the presence of HMB-45-positive cells within the tumor clearly established the diagnosis of hepatic AML. Any fatty tumor or focal fatty lesion of the liver that superficially resemble true lipomas should be tested for the presence of HMB-45-positive SMC in the tumor to differentiate it from AML.     

Intramuscular dendritic fibromyxolipoma: Myxoid variant of spindle cell lipoma?

Dendritic fibromyxolipoma (DFML) is an uncommon, recently described, benign soft tissue lesion that shares many clinical and pathological features with myxoid variants of spindle cell lipoma (SCL). As described, DFML is distinguished from SCL by the presence of dendritic cytoplasmic processes, abundant keloidal collagen and a prominent, often plexiform vascular pattern. We describe the first known reported case of an intramuscular DFML that occurred in the right shoulder region of a 73-year-old man. The tumor displayed the typical histopathological features of DFML but also included foci of chondroid metaplasia, a previously unreported finding. This report also discusses the differential diagnosis, particularly distinguishing DFML from SCL and myxoid liposarcoma. In view of the similarities in many clinical and pathological features between SCL and DFML, we speculate that DFML probably represents an unusual variant of myxoid SCL.     

Are the metabolic characteristics of congenital intraspinal lipoma cells identical to,or different from normal adipocytes?

Congenital intraspinal lipomas are frequently responsible for progressive neurological deficits caused by distortion or compression of the nervous system. Since fat metabolism in these lesions has not been previously studied, the aim of this study was to determine whether intraspinal lipoma cells behave like lipomas or like normal adipocytes. In 11 patients, intraspinal lipoma cells were compared with normal adipocytes isolated from adjacent subcutaneous adipose tissue for the following parameters: lipoprotein lipase (LPL), lipogenesis from U¹⁴C glucose, ß-receptor number, adenylate cyclase activity, cyclic AMP production, and lipolysis in response to ß- and ₂-adrenergic agonists. No significant difference between these two cell populations was found, suggesting that intraspinal lipomas are not lipomatous tumors, but hamartomatous lesions capable of growth and regression along with the changes in the rest of the fatty pool. This emphasizes the danger of an abnormal weight gain, as well as the possible usefulness of an hypocaloric diet in patients who worsen in spite of previous surgery.Research supported by INSERM (CRL 824005 and CRE 854010) and the D.G.R.