DIAGNOSIS OF INFECTIOUS AGENTS BY TISSUE CYTOLOGY - CHALLENGING CASES

摘要

Collection technique is often selected based on operator preference/experience and specific circumstances, e.g. ultrasound-guided collection. Fine needle aspiration of most tissues and organs can be performed either with or without suction applied viasyringe. A 12-cc syringe is a useful general-purpose size for FNA. If suction is not used, it is convenient to aspirate a few cc's of air into the syringe prior to aspiration, to facilitate expelling the sample onto the slide. Careful preparation of thesmear following FNA is critical. If smears are insufficiently smeared, the material may be too thick to evaluate. Conversely, fragile cells can easily be ruptured during smearing. If cell disruption is a recurrent problem, one useful technique is to usea coverslip to smear the material onto the slide. The coverslip can be stained and read in-house, and the slide can be submitted to a referral laboratory if indicated. Referral laboratories generally do not accept coverslip smear submissions for cytology.Other techniques include swabbing a lesion then rolling the swab onto a slide; scraping a lesion then smearing the material on a slide; and making imprints/impressions by dabbing a biopsy tissue/ gently onto the slide, or alternately blotting the slide directly on the cutaneous lesion (see Table 1.1 in ). Fluids are generally handled in a standard fashion: a direct smear is first made, then (if possible) automated cell counts are obtained and concentrated smears are prepared based on the nucleated cellcount. Collection technique may be optimized by use of endoscopy for direct visualization in some sites, e.g. nasal passages. One study found a marked improvement in sensitivity of cytology for detection of fungal hyphae when nasal samples were collected using rhinoscopy for visualization of lesions.