{'fraction_non_alphanumeric': 0.02113323124042879, 'fraction_numerical': 0.0018376722817764165, 'mean_word_length': 5.173913043478261, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Contemporaneous H&E sections should be standard practice in diagnostic immunopathology.

To the Editor: This letter is a plea and a reminder to colleagues about the importance of obtaining a contemporaneous hematoxylin and eosin (H&E) recut whenever immunohistochemistry (IHC) stains are ordered. The use of IHC as an adjunctive diagnostic tool in surgical pathology has become ubiquitous. About 15% of cases received by this service include immunostains. Regrettably, we rarely find a contemporaneous H&E recut among the slides provided for review. The importance of having a contemporaneous H&E recut is demonstrated by a consultation case illustrated here in which the interpretation of a dramatically different new finding was significantly hampered by the absence of a contemporaneous H&E recut slide. A 63-year-old woman underwent an excisional biopsy for a palpable breast mass. The original H&E-stained sections showed in situ carcinoma involving terminal ducts and lobules, which could be either ductal or lobular type (Figs. 1A, B). Recut slides prepared for IHC showed the in situ carcinoma to be E-cadherin negative, a result indicative of lobular carcinoma in situ. Also observed in the E-cadherin–stained recut section was a focus where the carcinoma cells appeared to extend beyond a lobular gland (Figs. 1C, D). No contemporaneous H&E recut was available, and a diagnosis of microinvasive carcinoma was of necessity made solely on the basis of the IHC section. Instances in which new diagnostic findings have appeared on H&Estained recut slides are familiar to all diagnostic surgical pathologists. The fundamental reason for ordering H&E recuts when faced with a challenging diagnostic problem is the expectation that the additional slides may uncover new findings. The circumstances in which IHC stains are obtained do not differ substantially. With few exceptions such as sentinel lymph nodes when predetermined immunostains are often ordered as the tissue is processed, IHC is ordered after H&E slides have been made and examined microscopically. Hence, the request for immunostains entails making new recut slides. The appearance of tissue can change subtly or very dramatically in recut IHC slides because they provide a view of tissue embedded deeper in the paraffin block. For this reason, an H&E stain should always be performed on one of the new consecutive sections created when immunostains are prepared to be able to fully evaluate new findings that may emerge in the recut material. This will prevent the delay created when the H&E recut must be ordered subsequently and the possibility that the area of interest will appear different or no longer be present when a later, now noncontemporaneous H&E recut is obtained. This standard should be adopted by hospital and commercial laboratories, which perform IHC for diagnostic purposes. Although the aforementioned example was drawn from our experience in breast pathology, the recommended practice (now our standard procedure) has implications for diagnostic surgical pathology of all organs. The significant contribution of IHC is not to be minimized, but it is widely acknowledged that IHC remains an adjunct to H&E stained preparations in most areas of diagnostic surgical pathology.