ABSTRACT
Introduction: Optimal orientation of minute mucosal biopsies is essential for a defi nite diagnosis in gastrointestinal pathology or to visualize neural plexuses in Hirschsprung disease. The problem of minute size of the biopsy and its orientation gets compounded when they are from neonates and mandates exhaustive strip cuts, thus delaying reporting. Aim: A modifi ed agar-paraffi n technique is aimed to make tissue embedding effi cient and user-friendly by inking mapping biopsies (one or more) either fresh or fi xed with surgical coloring inks followed by embedding fi rst in agar after orientation and followed thereafter by processing, re-embedding in paraffi n wax, sectioning and staining. Results: The tissues in agar paraffi n block were found to be well processed, fi rm, held secure and well preserved. The blocks were easy to cut, with serial sections of thickness 2-3 μ and easy to spread. The colored inks remained permanently on the tissues both in the block as well as on the sections which helped in easy identifi cation of tissues. Agar did not interfere with any stain such as Hematoxylin and Eosin or with histochemical stains, enzyme histochemistry or immunohistochemistry. Inking biopsies and pooling them in a block when obtained from the same patient reduced the number of tissue blocks. Conclusion: The modifi ed agar-paraffi n embedding technique is a simple reliable user friendly method that can greatly improve the quality of diagnostic information from minute biopsies by optimal orientation, better quality of sections, faster turnaround time and cost-effectiveness by economizing on the number of paraffi n blocks, manpower, chemical reagents and laboratory infrastructure
ABSTRACT
Background: Acetylcholinesterase (AChE) histochemistry on rectal mucosal biopsies accurately diagnoses Hirschsprung disease (HD), but is not widely employed as it requires special tissue handling and pathologist expertise. Calretinin immunohistochemistry (IHC) has been reported to be comparable to AChE staining with the loss of expression correlating with aganglionosis. Aim: The aim was to evaluate calretinin IHC as a primary diagnostic tool in comparison to the improvised rapid AChE technique in the diagnosis of HD. Materials and Methods: A total of 74 rectal biopsies (18 fresh frozen - 18 cases, 56 formalin fixed - 33 cases) from 51 cases of suspect HD were evaluated with hematoxylin and eosin/AChE/Calretinin. Ten biopsies each from ganglionated and aganglionated segments served as positive and negative controls. Ileal (3), appendiceal (3) and ring bowel (2) biopsies were also included. Two pathologists blinded to the clinical details evaluated the histomorphology with AChE and calretinin. Observations were statistically analyzed and Cohen’s κ coefficient employed to assess agreement between two pathologists and calretinin and the AChE. Results: The study confirmed HD in 26 and non-HD in 25 cases. There were 7 neonates, 5 low level biopsies and 14 “inadequate” biopsies. The results of calretinin were comparable with AChE with a statistically significant measure of agreement of κ = 0.973 between the two. One false-positive case of HD was noted with calretinin. The advantages and disadvantages of calretinin versus AChE are discussed. Conclusion: Calretinin is a reliable single immune marker for ruling out HD by its specific positive mucosal staining of formalin fixed rectal biopsy. The improvised AChE staining remains indispensable to confirm HD on fresh biopsies and thus, along with calretinin IHC maximizes the diagnostic accuracy of HD in difficult cases.