Classification of melanoma in adults and children.

After a brief history of the classification of melanoma in adults, this chapter describes the major features of the classic histogenetic types as well as of uncommon variants. Particular attention is paid to the meaning of controversial terms such as "minimal deviation" and "borderline." Specific problems associated with the classification of melanoma in children are also addressed, along with interpretation of atypical lesions resembling Spitz nevi.

Scarless wound repair: a human fetal skin model.

Animal studies demonstrate that the fetus heals cutaneous wounds by reformation of normal tissue architecture without scar formation. We have developed a new model to study human fetal skin wound healing. Grafts of human fetal skin placed onto athymic mice retain the morphologic features of normal development, although they differentiate at an accelerated rate when placed cutaneously compared to subcutaneously.

MR imaging of spindle cell hemangioendothelioma.

Spindle cell hemangioendothelioma is a slowly progressing vascular tumor of low grade malignancy. This neoplasm has been reported in 33 patients but in only one patient were osseous lesions seen. The only other description regarding imaging of this tumor was CT demonstrating soft tissue masses in the thigh without osseous involvement.

Clinical and pathological features of bacillary peliosis hepatis in association with human immunodeficiency virus infection.

Background: Peliosis hepatis is characterized by cystic, blood-filled spaces in the liver and is seen in patients with chronic infections or advanced cancer and as a consequence of therapy with anabolic steroids. Cutaneous bacillary angiomatosis is a bacterial infection that occurs in patients with human immunodeficiency virus (HIV) infection; its histologic appearance is that of a pseudoneoplastic vascular proliferation.

Methods: We studied liver tissue from eight HIV-infected patients with peliosis hepatis, two of whom also had cutaneous bacillary angiomatosis.

Hematologic aspects of human immunodeficiency virus infection: laboratory and clinical considerations.

Hematologic abnormalities are common in patients with HIV infection. This review will focus on HIV-associated cytopenias and coagulation abnormalities. Their occurrence, laboratory evaluation, and clinical significance and the mechanisms underlying their development are discussed.

Knotted DNA from bacteriophage capsids.

The majority of the DNA prepared from tailless capsids of bacteriophage P2 by the phenol extraction procedure consists of monomeric rings that have their cohesive ends joined. Electron microscopic and ultracentrifugal studies indicate that these molecules have a complex structure that is topologically knotted; they have a more compact appearance and a higher sedimentation coefficient when compared with regular nicked P2 DNA rings. Linearization of these rings by thermal dissociation or repair of the cohesive ends by DNA polymerase I in the presence of all four deoxynucleoside triphosphates gives molecules that are indistinguishable from normal P2 DNA that has been similarly treated.