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Animal models of osteonecrosis of the femoral head are indispensable to the understanding of successful treatment modalities for avascular necrosis of the femoral head in adults and in children with Legg-Calvé-Perthes disease. Many of these models adequately reflect the current “vascular deprivation” theory regarding the etiology of the disease. In addition to spontaneous occurrence, surgical- and corticosteroid-induced models are suitable, common experimental ones. Osteonecrosis of spontaneously hypertensive rats appears to be due to defective bone formation and compression of the arteries entering the femoral head at its lateral facets by daily weight-bearing loads. Successful modeling of surgical-induced femoral capital necrosis can be a challenge in animals with a dual epiphyseal blood supply. High doses of corticosteroids are a pivotal risk factor in the development of osteonecrosis. The pathogenesis of corticosteroid-induced osteonecrosis likely resides in reduced blood flow. Steroids may reduce blood flow by numerous mechanisms, including marrow adipocytic hypertrophy leading to sinusoidal compression, venous stasis and, eventually, obstruction of the arteries, and arterial occlusion by fat emboli and lipid-loaded fibrin-platelet thrombi. Other, less common varieties of osteonecrosis include those secondary to endotoxin-induced disseminated intravascular coagulation, immune reactions, immoderately low or high temperatures, and high-impact-related injuries. Common to these diverse forms of osteonecrosis are fibrin thrombi clogging arterioles and small arteries.

Aims To explore the potential of histomorphometric analysis in distinction between follicular adenomas and well differentiated follicular carcinomas of the thyroid gland. Their differentiation on routine histological study may be a challenging exercise, being contingent upon the absence or presence of vascular invasion and penetration of neoplastic follicles through the capsule of the tumour. Methods and results Computer-assisted image analysis was performed to gauge the nuclear area, nuclear Ferret diameter, nuclear regularity factor, nuclear elongation factor, number of nuclear vesicles and total area of all nuclear vesicles in the follicles of 37 adenomas and 36 well differentiated carcinomas. By univariate analysis, these nuclear descriptors (with the exception of the elongation factor) were found to correlate with the benign or malignant nature of the tumours. By multivariate analysis, only the nuclear area, Ferret diameter and regularity factor were ascertained to be significant predictors of malignancy. A fitted logit model correctly predicted 91% of the cancers and 87% of the adenomas. Conclusions Histomorphometrically gauged nuclear parameters of the tumour cells may reinforce pathologists' decision-making by adding objective and unbiased criteria to their subjective assessment of follicular neoplasms in cases in which vascular or capsular invasion are not detected.

Progressive diaphyseal dysplasia is a rare osteosclerotic dysplasia of the bone which presents clinically with bone pain, muscle weakness and a waddling gait. Radiography, which shows progressive hyperostosis along the long bones forms the basis of the diagnosis. We present a young patient in whom pain and limitation of movement in the shoulder joint area, mimicking capsulitis, were the presenting symptoms of the disease. The diagnostic and the therapeutic approach to this unusual disorder are discussed.

A 59-year-old patient is reported with a protruding, mucosal nodule within the mandibular alveolar fold. Histological examination of the excised mass disclosed angiolymphoid hyperplasia with eosinophilia (histiocytoid hemangioma). Though the lesion was not completely excised and invaded the adjacent muscle of the floor of the mouth, there was no recurrence during a follow-up period of 17 months.

A 52-year-old patient underwent excision of a parotid lump which was fond to consist of a Warthin’s tumor coexistent with a lymph node involved in dermatopathic lymphadenopathy. A preoperative fine-needle aspiration specimen contained brown pigment-granule-laden macrophages within the background of many lymphocytes. Failure to correctly diagnose the parotid tumor was likely due to a sampling error.

Purpose: The aim of this work was to detect nuclear parameters related to the prognosis of patients with stage III, IV or DS neuroblastomas. Methods: Histological sections of 25 operation specimens obtained from children with advanced-stage neuroblastomas were subjected to computer-assisted image analysis. Statistical relationships between nuclear descriptors of the tumor cells and patients' clinical outcome were determined. Results: The coefficient of variability of the mean nuclear area the mean nuclear elongation factor, and the mean nuclear averaged Feret diameter of the neuroblastoma cells were ascertained to be discriminators separating high-grade from low-grade tumors. Conclusions: The histomorphometrically gauged nuclear parameters may help oncologists to assess the prognosis of patients with advanced-stage neuroblastoma.

A leiomyoma of the fetal membranes was incidentally discovered on examination of a spontaneously expulsed placenta following an uneventful pregnancy and delivery of a healthy neonate. Perusal of the literature uncovered only a single report of a placental leiomyoma.