Bone marrow edema signal can be seen in many settings ranging from trauma and arthritis to less common conditions including transient osteoporosis, transient bone marrow edema syndrome, true osteonecrosis, spontaneous osteonecrosis, and shifting bone marrow edema. Terms such as spontaneous osteonecrosis of the knee (SONK) appear frequently in the radiology and orthopedics literature but are rarely described on true, histologic basis. This article reviews the less frequently encountered and less well understood entities and explores their potential pathophysiologies and significance.

Lesions that involve the cortex of the tibia are fairly common in radiology practice. However, the number of diseases that involve the tibial cortex is great, and it can be difficult to arrive at a limited differential diagnosis from radiographic findings. Categorization of lesions of the tibia into those that cause cortical destruction and those that cause cortical proliferation can help narrow the broad differential diagnosis. Lesions that cause cortical destruction include nonossifying fibroma, fibrous dysplasia, osteofibrous dysplasia, aneurysmal bone cyst, giant cell tumor, eosinophilic granuloma, Ewing sarcoma, neurofibromatosis, adamantinoma, osteoblastoma, chondromyxoid fibroma, hemangioendothelioma, renal cell metastatic disease, hemangioma, and hemangiopericytoma. Lesions that cause cortical proliferation include osteochondroma, stress fracture, osteoid osteoma, periosteal osteogenic sarcoma, diaphyseal dysplasia, venous stasis, cellulitis, chronic osteomyelitis, osteopathia striatum, and melorheostosis. Conventional radiography along with clinical and pathologic data can aid in diagnosis of the wide variety of disease processes that involve the tibial cortex.

Subscapularis tear is frequently missed on MRI. Recognizing that primary signs of tear may be limited to the cranial third of the subscapularis tendon and identifying associated signs should facilitate diagnosis.

On MR images, impaction fractures demonstrate prominent marrow edema, and distraction fractures demonstrate minimal edema. Impaction fractures are more often missed on plain radiographs, and distraction fractures are more often missed on MR images. Segond fractures should be suspected if MR images show lateral capsular ligamentous injury in the knee; in these cases, evaluation with plain radiography is warranted.

We present a case of de novo polymorphous low-grade adenocarcinoma (PLGA) arising in a minor salivary gland with a relatively large radiographic extent compared with that of most of the PLGAs reported. This paper describes the radiographic extent of the lesion and the findings of CT imaging.

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The distribution of various glycoprotein molecules on the surface of follicular keratinocytes was studied with a panel of lectins with specificity for various sugar moieties on biopsy specimens from both bald/balding scalp and normal occipital scalp, of 23 patients with androgenetic alopecia as well as on biopsies of normal forearm skin of four patients. The most significant differences between bald and normal scalp biopsy were noted with Ulex europaeus agglutinin I (UEA I). We noted an increased (91.8% +/- 3.1; mean +/- SE) expression of UEA I binding sites on the infra-infundibular follicular keratinocytes in anagen terminal scalp hairs, compared to 28.5% +/- 5.2 in the indeterminate (anagen) hairs of balding scalps, and 23.2% +/- 6.3 in the anagen follicles of vellus fore-arm hairs. By contrast, the telogen hairs demonstrated minimal UEA I staining: 4.0% +/- 0.8, mean +/- SE in telogen scalp hairs, 1.8% +/- 0.5 in telogen hairs of balding scalps (0% in completely bald scalps, in which all the hairs were in the telogen phase), and 1.9% +/- 0.2 in telogen forearm hairs. The percentage of UEA I staining correlated with the length of the infra-infundibular follicles in all cases studied. In three cases of hair regrowth after hair growth promotors, the UEA I staining increased to 80.6% +/- 6.1 in anagen hairs and correlated with increased length of infra-infundibular follicles. Our data indicate that there are 1) marked differences between anagen and telogen follicles in UEA I binding to infra-infundibular follicular keratinocytes; 2) the percentage of UEA I staining reflects the size (length) of the infra-infundibular hair follicle; and 3) the anagen follicles of balding scalps (indeterminate hairs) show UEA I staining resembling that exhibited by anagen follicles of vellus hairs.