Peripheral Villous Stromal Hyperplasia: A Distinctive Placental Lesion in Hemoglobin Bart Hydrops Fetalis
Bibliographic record
Abstract
In hydrops fetalis (HF) the placenta can be markedly enlarged and the villi show stromal edema, increased Hofbauer cells, and reduced numbers of capillaries. Hemoglobin (Hb) Bart is the most severe form of thalassemia, causing HF due to profound anemia. We report a previously undescribed histologic finding based on a review of Hb Bart HF cases, termed "peripheral villous stromal hypercellularity." This change was noted in 15 of 18 (83%) placentas with Hb Bart HF but not in placentas of 21 cases of HF due to other causes, including 11 cases involving anemia. The hyperplastic stromal cells were determined to be myofibroblastic by immunohistochemistry and electron microscopy, associated with a more complex capillary network in villi than is seen with other causes of HF. The authors hypothesize that this angiogenesis in villi is a response to fetal anemia from Hb Bart. In turn, there is increased villous blood flow, resulting in edematous villous stroma, leading to narrowing of the intervillous space in the placenta. Hyperplasia of myofibroblasts might then be a compensatory change, in that contraction by these cells would reduce the vascular lumina and the size of placental villi, thereby widening the intervillous space to improve capacity for maternal blood circulation. Curiously, this histologic change was restricted to cases of HF caused by Hb Bart. We speculate that in Hb Bart disease, the hypoxia and hydrops develop earlier in gestation, compared to other causes of HF, allowing the time for these adaptive changes to occur in the placenta.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".