Thickening of the basement membrane as a diagnostic sign of mycosis fungoides.

The epidermal basement membrane (BM) is readily identified on skin biopsy specimens stained with periodic acid-Schiff (PAS) and PAS with diastase (PAS-D). Thickening of BM can be evidenced in several inflammatory and tumoral conditions. We noticed that most of our biopsy specimens of mycosis fungoides (MF) showed thickening of the BM. We decided to retrospectively study BM thickness in 27 biopsy specimens of MF and compare them with 27 cutaneous biopsy specimens of inflammatory diseases. We studied PAS and PAS-D stains in all cases and we measured BM thickness with an ocular micrometer. Cases were scored in a four-tiered system: 0: no detectable staining; 1+ (mild: < 5 µm); 2+ (moderate: 5-9 µm); and 3+ (prominent: >9 µm). The difference between both groups (MF vs controls) was highly significant for BM thickness values by both one- and two-tailed t tests (P < 0.0006). While only 3 biopsy specimens from the controls (11.11%) showed areas of 3+ thickening, 12 biopsy specimens of MF (44.44%) showed areas of 3+ thickening, and most cases showed diffuse, at least 2+ thickening, while the controls showed more segmental, mostly 1 or 2+ staining. We conclude that thickening of BM can be useful in the differential diagnosis with inflammatory conditions.

Effects of various fixatives and temperature on the quality of glycogen demonstration in the brain and liver tissues.

The visualization of glycogen deposits in cells and tissues is important for studying glycogen metabolism as well as diagnosis of glycogen storage diseases. Evidence suggests that the demonstration of glycogen can better be enhanced by factors such the choice of fixative and temperature during fixation. Here, we assessed efficacy of neutral buffered formalin (NBF), alcoholic formalin (AF) and paraformaldehyde (PFA) at 4 °C, 37 °C and 40 °C using Periodic Acid Schiff's staining method. Each liver specimen was fixed in NBF and AF while the brain tissues were fixed in NBF, AF and PFA. We found that there was a better PAS staining intensity with the liver tissues fixed in AF compared with NBF. Also, there was no difference in the quality of the staining for tissues fixed in AF at 37 °C, 4 °C and 40 °C, but fixation with NBF at 4 °C gave the best staining quality when compared with 40 °C and 37 °C. Furthermore, hippocampal tissues fixed in AF showed better quality of PAS staining compared with NBF and PFA. A significant increase in staining intensity was observed for PFA when compared with NBF. Superior staining intensity for PAS was observed at 4 °C for hippocampal tissues fixed with NBF, AF and PFA. Taken together our results show that AF at a temperature of 4 °C gave the best result. Hence, glycogen demonstration can better be enhanced by the choice of fixative and temperature during fixation.