Minimal deviation spindle cell melanoma: unusual histologic pattern in an 11-year-old black girl

An 11-year-old black girl presented with a nodule at the tip of the left thumb that eroded the underlying tip of the distal phalanx. The tumor was composed of junctional nests and uniform atypical spindle melanocytes that formed broad fascicles and diffusely permeated the dermis. Scattered collections of Kamino bodies were present. A single enlarged left axillary lymph node was noted 9 months after the initial presentation. The lymph node measured 7 x 4.5 x 2.5. cm and was replaced by metastatic tumor composed of fascicles of spindle melanocytes. Immunohistochemical examination demonstrated immunoreactivity for S100, HMB45, and Leu 7, and ultrastructural examination revealed the presence of premelanosomes in the primary and metastatic tumor. Now, more than 10 years since her initial presentation, the patient is well with no further manifestation of the disease.     

Lung lesions: correlation between viewing time and detection

The influence of viewing time on the detectability of subtle and obvious lung cancers was studied. Frontal chest radiographs of 40 patients with subtle cancers, 40 patients with obvious cancers, and 40 healthy control subjects were shown to four observers for four different viewing times (0.25 second, 1 second, 4 seconds, and unlimited time). Receiver operating characteristic analysis was used to compare the detectability of lesions. Performance was degraded as viewing time decreased. The true-positive fractions for subtle and obvious cancers were 30% and 70% at 0.25 second and 74% and 98% at unlimited viewing time, respectively, for a given false-positive fraction of 20%. Thus, even with unlimited viewing time, the false-negative fraction for subtle cancers was 26%. The difference in detectability between subtle and obvious lung cancers was exaggerated at 1.0 second compared with 4 seconds and unlimited viewing time. The following conclusions were reached: (a) a substantial proportion of subtle lung lesions are missed, even with unlimited viewing time; (b) a large proportion of obvious lung cancers are detected with flash viewing; (c) the detectability of lesions decreases considerably as viewing time becomes less than 4 seconds; and (d) differences in detectability are exaggerated by short viewing times.     

Measurement of femoral torsion: comparison of standard roentgenographic techniques with ultrasound

Measurement of femoral torsion by ultrasound was compared with measurements by standard roentgenographic techniques in a femoral model and in a clinical study. Magilligan, Ryder-Crane, and fluoroscopic determinations on the femoral model demonstrated acceptable interobserver and intraobserver variance. With high degrees of femoral torsion, ultrasound readings were less accurate and significantly lower than the actual angle of femoral torsion. In the clinical study, ultrasound measurements were compared with Magilligan measurements in 29 hips. Similar to the model, ultrasound readings were lower and discrepancy was greater at higher angles of torsion.     

Isolation and characterization of expression cDNA clones encoding antigens of Onchocerca volvulus infective larvae.

The isolation of recombinant cDNA clones expressing antigens found in Onchocerca volvulus infective larvae is described. To isolate such clones, an expression cDNA library constructed from adult O. volvulus RNA was screened with antiserum raised against infective larvae. One clone, designated lambda RAL-1 was characterized further. The recombinant antigen produced by lambda RAL-1 stimulates proliferation of peripheral blood mononuclear cells from O. volvulus infected humans. Lambda RAL-1 is derived from a 1450 bases message that encodes a protein with an apparent molecular weight of 42,000 in adult O. volvulus. The inserted DNA of lambda RAL-1 contains an open reading frame of 1008 bp. The amino acid sequence predicted by this open reading frame contains three repeats of the sequence KKPEDWD. The identification of clones such as lambda RAL-1 will provide quantities of purified antigens sufficient to begin to study the immune response to and explore the development of immunity against the infectious form of the parasite.     

The RBE of the leakage radiation from the Hiletron neutron therapy unit

The RBE of the leakage radiation from the Hiletron 14.7 MeV neutron therapy unit has been measured using three sensitive biological systems in mice, which differ markedly in their radiobiological characteristics. These systems comprise type A spermatogonia and bone marrow stem cells, which are affected insignificantly by dose rate, and pigment abnormalities in hair follicles which are affected markedly by dose rate. For mice irradiated at 10 cm depth in a water phantom, the leakage radiation up to 40 cm from the beam axis was virtually as effective as the primary beam for the latter two biological systems, and for spermatogonia in mice when irradiated in air. At this distance, the total dose rate was about 0.2 cGy (rad) per minute (3% of that in the primary beam), and the gamma-ray component was about 70%. This equal effectiveness of the total dose for all three systems was considered fortuitous, and it implied high RBE values for equal effect with the small neutron component at far distances. Considering published data on RBE versus neutron energy, the evidence suggested either a positive interaction of neutron and gamma-ray components in killing bone marrow stem cells when the neutron component was less than 40% of the total dose, or an increased efficiency of neutrons when delivered at very low dose rates. However the components were additive in killing spermatogonia.