Debra S. Heller

Pitfalls in Frozen Section: A Case of Incidental Papillary Mesothelioma

Well-differentiated papillary mesothelioma is an uncommon benign, although potentially recurrent mesothelial lesion that occurs in the peritoneum of women over a wide age range. We recently encountered an incidental case sent for frozen section at the time of hysterectomy for endometrial carcinoma. Familiarity with this lesion will help prevent overinterpretation as a serous carcinoma.

A Deceptive Spread: Myoinvasion of Endometrial Carcinoma Imitating Adenoma Malignum

Endometrioid type of endometrial carcinoma is the most common form of uterine malignancy. The majority of patients in the developed world present with the low-grade, low-stage type of this malignancy. The current treatment of early-stage endometrioid carcinoma provides most patients with a favorable outcome. One of the important factors that determine the outcome of early-stage endometrial carcinoma is the involvement of cervical stroma. One of the very rare forms of cervical stromal involvement by endometrioid carcinoma is termed “adenoma malignum type” invasion due to its similarity to the infamously deceptive type of cervical adenocarcinoma called adenoma malignum. Since adenoma malignum is often discovered incidentally, finding adenoma malignum type of myoinvasion may deceive a pathologist to diagnose the simultaneous presence of endometrial carcinoma and adenoma malignum in the same patient as 2 separate entities. Also, this type of myoinvasion may be missed altogether for its subtle nature. In this article, we report a case of low-grade, low-stage endometrioid carcinoma with adenoma malignum type of myoinvasion. We have pointed out the subtle nature of this lesion and the important features to remember to successfully identify it.

Pitfalls in Pathology—Nodular Hyperplasia of Bartholin's Gland

Nodular hyperplasia of the Bartholin's gland is an underreported and extremely rare entity that presents as a solid lesion potentially raising concern for malignancy clinically, most solid lesions at this location are carcinomas. They may also be mistaken for a Bartholin cyst clinically. Nodular hyperplasia is rarer than carcinoma of the Bartholin gland, and hence pathologists may not be familiar with this entity, making it a pitfall in pathologic as well as a clinical diagnosis. Here we report a case originally considered a Bartholin cyst, but raising intraoperative concern due to solid elements. Histological examination of the lesion revealed nodular hyperplasia of Bartholin's gland. Recognition of this entity is important, as it is something that may be encountered by the pathologist.

Use of p53 immunohistochemistry can improve diagnostic agreement for differentiated vulvar intraepithelial neoplasia ( dVIN ): an international reproducibility study

Aims Differentiated or HPV‐independent vulvar intraepithelial neoplasia (dVIN) can progress rapidly to invasive cancer and accurate pathological diagnosis is essential to facilitate appropriate interventions. Histological similarities of dVIN with non‐neoplastic lesions, however, often make the diagnosis less reproducible. We investigated among a diverse group of pathologists whether the diagnostic agreement improves with the use of p53 immunohistochemistry (IHC) interpreted using the pattern‐based schema. Methods and results Fifty haematoxylin–eosin (HE) stained archival slides (30 dVIN and 20 non‐dysplastic vulvar lesions) were selected and p53‐IHC was performed. Twenty‐four board‐certified pathologists from eight countries first assessed the HE slides alone, and after a washout period, re‐evaluated them alongside the p53‐IHC slides. During both rounds, slides were diagnosed as dVIN, favour dVIN, favour no‐VIN or no‐VIN. p53‐IHC was scored as wild‐type or mutant (diffuse, basal, cytoplasmic or null). Kappa ( κ ) statistics and McNemar's test were used for statistical analyses. Overall diagnostic agreement for dVIN saw a significant increase in the Kappa value ( κ  = 0.6 vs. κ  = 0.4, P  = 0.002) when HE and p53‐IHC slides were assessed together compared with histology assessment alone, although the level of agreement remained moderate. For p53‐IHC assessment, overall agreement was substantial ( κ  = 0.7). Diagnoses changing from no‐VIN/favour no‐VIN to dVIN correlated significantly with the identification of a p53‐mutant pattern ( P  < 0.001). Conclusions Our findings indicate that p53‐IHC is a robust ancillary tool that can be reproducibly interpreted by pathologists with varying experience levels and supports the routine use of p53‐IHC in cases where dVIN is considered in the differential diagnosis.