Although knowledge of basic genetics in the field of sclerosing bone dysplasias is progressing, the radiologist still plays a pivotal role in the diagnosis of this relatively poorly understood group of disorders. Based on a target site approach, these anomalies are classified into three groups. Within each group, further differentiation can be made by distinctive clinical findings and by mode of inheritance: (a) dysplasias of endochondral bone formation: osteopetrosis (Albers-Schönberg disease), pycnodysostosis, enostosis, osteopoikilosis, osteopathia striata (Voorhoeve disease); (b) dysplasias of intramembranous bone formation: progressive diaphyseal dysplasia (Camurati-Engelmann disease) and variants, hyperostosis corticalis generalisata (Van Buchem disease) and variants; and (c) mixed sclerosing dysplasias: melorheostosis (Leri disease) and overlap syndromes.

A 28-year-old man presented with a swelling at the right thoracic wall. Computed tomography showed an aggressive process involving the cortex of the rib with concomitant soft tissue mass. However, a needle biopsy specimen revealed an enchondroma and consequently the physician decided to apply a "wait-and-see" strategy. After 3 years of careful follow-up by MR imaging, the patient complained of subtle enlargement of the lesion, which was later confirmed on repeated CT scan. Despite an aggressive appearance on control MR imaging, histopathological examination after incisional biopsy could not differentiate between enchondroma and low-grade chondrosarcoma. Wide excision including previous biopsy trajectory was performed. Diagnosis of a low-grade (grade I) chondrosarcoma was made on findings of the excisional specimen and seeding of cartilage tissue along the previous incisional biopsy trajectory was found.

A 65-year-old woman presented with progressive swelling of the anterior aspect of both legs, the dorsal aspect of the feet (Fig. 1a), and the fingers, together with clubbing of the last (Fig. 1b). These features had been present for 4 years but she had only recently developed discomfort and pain in her feet from pinching shoes. The overlying skin was indurated with red-purple discoloration. A localized nodular thickening sharply demarcated from the surrounding skin surface was seen on the dorsal aspect of both feet (Fig. 1a).The patient's past medical history was unremarkable except for hyperthyroidism of Graves, which she had had for 10 years and for which she had received treatment with iodine-131 on three occasions. The last dose of iodine-131 was administered a year before the present hospital presentation. She was currently euthyroid taking thyroxine replacement therapy.On physical examination the thyroid gland was normal. Marked exophthalmos had been present from the onset of Graves' disease but did not required surgical therapy. On CT scan of the orbit, marked proptosis was confirmed (Fig. 2a), as well as thickening of the extraocular muscles (Fig. 2b).Laboratory examination of the thyroid function revealed a suppressed thyroid-stimulating hormone level and an elevated titer of thyroid stimulating immunoglobulin.Radiographs of the hands revealed a bilateral feathery diaphyseal periosteal reaction on the radial side of the first and second Eur.Abstract Thyroid acropachy is a rare manifestation of autoimmune thyroid disease, in the form of soft tissue swelling of the hands and feet with insidious onset, associated with clubbing and characteristic periosteal reactions. It is usually part of a syndrome consisting of a typical triad of thyroid acropachy, exophthalmos, and pretibial myxedema. The purpose of this case report is to demonstrate the imaging features of this typical triad in a 65-year-oldwoman. This case is the first in which the MRI features of thyroid dermopathy are documented.

The aims of this study were, firstly, to provide a formula (neurogenic index) based on MR characteristics used in daily routine for predicting whether a soft tissue tumor is neurogenic or not, secondly, to test prospectively the performance of this formula, and thirdly, to compare this performance with that of radiologists experienced in MR imaging of soft tissue tumors. Retrospectively, MR images of 70 neurogenic and 70 non-neurogenic soft tissue tumors were evaluated in random order by two teams of two observers each. A neurogenic index (NI) was calculated based on those MR parameters that showed no or minor interobserver variability. Subsequently, three investigators in concert used the NI in a validation group of 15 neurogenic and 22 nonneurogenic soft tissue tumors. The same team, based on their own experience, tried to differentiate in the same validation group neurogenic from non-neurogenic soft tissue tumors. This was expressed in a subjective score (SS). Sensitivity, specificity, and predictive values were calculated. NI comprised spread (intra- or extracompartmental), distribution, fluid-fluid levels, homogeneity on T2-weighted images (WI), highest signal intensity (SI) on T1WI, lowest SI on T2WI, and delineation on T2WI. In the validation group, NI had a sensitivity of 88.6%, a specificity of 52.0%, a positive predictive value (PPV) of 54.1%, and a negative predictive value (NPV) of 84.6% for neurogenic tumors. The subjective score SS was superior and had a sensitivity of 93.3%, a specificity of 77.2%, a PPV of 73.7%, and a NPV of 94.4%. Our NI was less accurate than the SS; however, the low number of false-negative diagnoses for neurogenic tumors warrants continued efforts in development of neural networks.