The edition · Pathology
Myositis markers on paraffin: when frozen muscle is not an option
A small validation shows MHC-II, MxA and p62 can be read on FFPE muscle; alongside, how poorly the WHO goblet cell grade reproduces, p53 as an early warning in PSC-IBD, a new BAP1-linked vulvovaginal tumour, and Rb in cervical neuroendocrine carcinoma.
The edition in brief
A Histopathology study of 20 muscle biopsies found MHC-II, MxA and p62 immunostains on formalin-fixed paraffin sections matched frozen sections in 90%, 90% and 80% of cases, while MHC-I and MAC failed on paraffin. Seven expert pathologists grading 20 appendiceal goblet cell adenocarcinomas with the three-tier WHO 5th edition system agreed on only four cases, with overall kappa 0.29. In PSC-IBD, aberrant p53 overexpression in benign colon biopsies taken about 20 months before dysplasia was found in 36% of patients who later developed dysplasia against 5% of controls, with specificity 95% and sensitivity 36%. A four-case series describes vulvovaginal epithelioid mesenchymal neoplasm with deciduoid morphology, ER/PR-positive, half with germline BAP1 variants. Among 29 cervical neuroendocrine carcinomas, 96% were high-risk HPV-positive, and HPV-positive tumours showed partial Rb loss, unlike the complete loss typical of lung small cell carcinoma. The pearl covers reading p53 immunohistochemistry patterns.
Grading goblet cell adenocarcinoma: experts agreed on one case in five
Report the proportion of high-grade pattern with the goblet cell adenocarcinoma grade, and seek a second opinion when the grade will decide surgery.
Aberrant p53 in benign colon biopsies flagged later dysplasia in PSC-IBD
Strong aberrant p53 in a benign PSC-IBD colon biopsy may mark higher dysplasia risk and is worth flagging, but a normal stain is not reassuring.
A new ER/PR-positive vulvovaginal tumour linked to germline BAP1
Stain for BAP1 in unusual epithelioid vulvovaginal tumours with deciduoid cytoplasm, and refer for germline testing if it is lost.
Rb staining separates cervical from lung small cell carcinoma
When site of origin of a small cell carcinoma is uncertain, use Rb pattern and HPV in situ hybridisation rather than p16 alone.
Reading p53 immunohistochemistry: three abnormal patterns
Treat both strong diffuse p53 and complete absence with a positive internal control as abnormal.
Myositis immunostains on paraffin muscle: three that work, two that do not
Laboratories without frozen muscle processing can consider paraffin MHC-II, MxA and p62 staining, validated locally, but not MHC-I or MAC.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this one is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for pathology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free