Quality control in diagnostic immunohistochemistry: integrated on-slide positive controls.

Standardization in immunohistochemistry is a priority in modern pathology and requires strict quality control. Cost containment has also become fundamental and auditing of all procedures must take into account both these principles. Positive controls must be routinely performed so that their positivity guarantees the appropriateness of the immunohistochemical procedure. The aim of this study is to develop a low cost (utilizing a punch biopsy-PB-tool) procedure to construct positive controls which can be integrated in the patient's tissue slide. Sixteen frequently used control blocks were selected and multiple cylindrical samples were obtained using a 5-mm diameter punch biopsy tool, separately re-embedding them in single blocks. For each diagnostic immunoreaction requiring a positive control, an integrated PB-control section (cut from the appropriate PB-control block) was added to the top right corner of the diagnostic slide before immunostaining. This integrated control technique permitted a saving of 4.75% in total direct lab costs and proved to be technically feasible and reliable. Our proposal is easy to perform and within the reach of all pathology labs, requires easily available tools, its application costs is less than using external paired controls and ensures that a specific control for each slide is always available.

Cell proliferation of squamous epithelium in gastro-oesophageal reflux disease: correlations with clinical, endoscopic and morphological data.

BACKGROUND: The microscopic assessment of squamous epithelium lesions in gastro-oesophageal reflux disease (GERD) is subjective. The Ki67 nuclear antigen expressed by proliferating cells provides an objective measure of regeneration in the squamous epithelium. AIM: To evaluate Ki67 expression in GERD patients and controls, in comparison with histological lesions, pH-metry and endoscopic data. METHODS: Eighty-seven patients with GERD symptoms and 20 symptom-free controls underwent endoscopy and 24-h pH monitoring. Oesophageal biopsies (4 cm, 2 cm and Z-line) were stained with Ki67/MIB-1 antibodies; the Ki67-positive nuclear area was assessed with an image analysis system and expressed as percentage of the whole epithelial area (Ki67-%). RESULTS: Ki67-% was significantly higher in 32 patients with erosive oesophagitis, 44 endoscopy-negative GERD and 11 patients with functional heartburn than in controls (P = 0.0001). Both controls and patients showed a progressive increase in Ki67-% from 4 cm to the Z-line (P < 0.0001). Ki67-% showed a significant correlation with other conventional histological lesions (P ranged between 0.0151 and <0.0001). CONCLUSIONS: Ki67 evaluation provides quantitative and objective data on squamous epithelium proliferative activity. This marker can be applied in the distinction of endoscopy-negative GERD from healthy controls.