Light Chain Proximal Tubulopathy: Expanding the Pathologic Spectrum with and without Deposition of Crystalline Inclusions

Light chain proximal tubulopathy (LCPT) is an uncommon form of renal disease associated with dysproteinemias. It is characterized by intracytoplasmic deposition of crystallized mostly kappa monoclonal light chains in proximal tubules (PTs). Crystals are located within lysosomes by electron microscopy (EM). Rare lambda LCPT cases without crystals by EM were described. Retrospectively, we reviewed clinical, light microscopic (LM), immunofluorescence (IF), and EM findings in 9 cases) (8 males, 1 female; mean age 57 years (38–81)) with multiple myeloma. LM showed abundant cytoplasmic droplets in PT cells in all cases. Droplets were also present in the podocytes, endothelial and parietal cells in one case. IF revealed staining of crystals with kappa in 3 and lambda in 6. EM showed electron dense rectangular, rhomboid, or needle shaped crystals in PT cells in 3 cases (33%), one of which had crystals in podocytes and interstitial cells. Six lambda LCPT cases showed no crystals by EM (67%). This may reflect differences in the physicochemical properties of light chains. The mechanisms of crystal accumulation in these cells and the significance of this finding are unknown.

Exploratory behavior in children

60 children representing equally two age groups (2nd and 6th graders) and three ability groups (IQs of 92–108, 112–128, and 132+) served as Ss in studies of the effects of stimulus characteristics on exploratory behavior and the effect of novelty on immediate and delayed recall. In Exp. 1, significant effects were obtained for complexity, abstractness, and incongruity but not ambiguity of tachistoscopically presented stimulus materials. Age affected exploration of incongruous and ambiguous but not complex and abstract materials. Ability level had no significant effects. In Exp. II, exploratory time and judged intensity of exploration were influenced by the characteristics of stimulus objects presented in an array for free exploration. Novelty facilitated exploration but neither age nor ability had a significant effect. In Exp. III, both immediate and delayed recall by the younger Ss were greater for objects they identified as “novel” but recall by the older Ss was somewhat greater for “not-novel” objects. Factor analysis of all the behavioral scores derived in these experiments along with scores from a creativity test indicated that the various measures of exploratory behavior and creativity used here were sampling different aspects of behavior and no one of such measures can be assumed to be an adequate index of exploratory behavior in general.