This Week in Pathology — May 21, 2026

Welcome to This Week in Pathology. This week we're covering 9 notable papers spanning novel diagnostic strategies, the role of the neuro-immune axis in disease, and new insights into systemic pathology. Let's dive in.

Novel Diagnostic Strategies First, we'll look at three papers pushing the boundaries of diagnostic precision, using artificial intelligence, novel reporters, and multimodal biomarkers. In breast pathology, a significant bottleneck is the time it takes to get ancillary studies, like hormone receptor and HER2 status, back on a new diagnosis of cancer. A study in *Histopathology* presents a practical solution to speed this up [2]. Investigators implemented an AI-based workflow where the AI system analyzed H&E slides from breast core biopsies. For cases with a high AI-based likelihood of invasive carcinoma, the Laboratory Information System was programmed to automatically order the standard biomarker panel, including ER, PR, HER2, and Ki-67, even before a pathologist reviewed the slide.

The Study This was a retrospective implementation study comparing a pre-implementation phase to a post-implementation phase. They measured the turnaround time from case assignment to the availability of the immunohistochemical stains and to the final reporting of those biomarkers.

Results Implementation of this AI-enhanced workflow led to a significant reduction in the time to biomarker reporting of approximately one full working day. Importantly, the system demonstrated high appropriate relevance, meaning it did not trigger unnecessary staining, thus maintaining diagnostic accuracy and avoiding waste. The clinical implication is clear: integrating AI directly into the LIS can optimize laboratory efficiency and deliver crucial results to the oncology team and patient more rapidly.

Moving from AI-driven workflows to novel molecular tools, a paper in *Science Translational Medicine* introduces a noninvasive method for detecting and staging kidney fibrosis, a common pathway for progressive chronic kidney disease [9]. Currently, assessing fibrosis requires an invasive kidney biopsy. To address this, researchers developed what they call fibrogenesis sensing reporters, or FSRs. These reporters are engineered to be non-fluorescent until they encounter the fibrotic kidney environment. Once injected, they are cleared by the kidneys and become activated by two enzymes that are upregulated in fibrosis: lysyl oxidase and transglutaminase 2. This activation unquenches a fluorophore that can be detected in the urine.

In a clinical cohort of 35 individuals, this FSR-based urinalysis could distinguish patients with chronic kidney disease from healthy controls with 84% sensitivity and 94% specificity. Even more impressively, it was able to discriminate between patients with histologically mild versus severe fibrosis. This is a crucial distinction that standard clinical metrics, such as estimated GFR, serum creatinine, and BUN, were unable to make. This noninvasive reporter has significant translational potential for early identification of renal fibrosis and for stratifying patients to guide clinical management.

Rounding out our diagnostics section, a study in *Nature Medicine* tackles the difficult differential diagnosis of neurodegenerative parkinsonian syndromes, where overlapping clinical features often make it hard to distinguish between conditions like Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy [10]. The authors evaluated a multimodal biomarker strategy. This involved combining two seed amplification assays—one for alpha-synuclein and one for 4-repeat tau, both performed on skin biopsies—with serum neurofilament light chain levels. In a cohort of 166 participants, the alpha-synuclein assay was highly sensitive for synucleinopathies, while the 4-repeat tau assay was highly sensitive and specific for progressive supranuclear palsy. Serum neurofilament light chain helped distinguish multiple system atrophy from Parkinson's disease. The key finding is that integrating these three complementary biomarkers significantly improved diagnostic discrimination compared to using any single marker alone. This supports a multimodal approach for a more precise, biologically-informed diagnosis of parkinsonian syndromes.

The Neuro-Immune Axis Next, a trio of papers highlights the growing understanding of the crosstalk between the nervous and immune systems in pathology. A fascinating study in *Cell* uncovers a mechanism by which nerves can directly promote lung cancer growth [6]. Investigators showed that in lung adenocarcinoma, the tumor progression leads to an amplification of local nociceptive, or pain-sensing, sensory nerves. These activated nerves release calcitonin gene-related peptide, or CGRP. This neuropeptide then acts on a subset of macrophages, which in turn impairs the recruitment of fibroblasts needed to build tertiary lymphoid structures. As these structures are key hubs of anti-tumor immunity and predictors of good prognosis, blocking their formation allows the tumor to grow more freely. The researchers also found that cigarette smoke extract further activates this neuro-immune circuit, providing a non-mutagenic mechanism by which smoking can promote tumorigenesis. In animal models, local sensory denervation or pharmacologic blockade of CGRP restored the formation of tertiary lymphoid structures, enhanced T-cell and B-cell dependent immunity, and suppressed tumor growth. This work identifies a critical neuro-immune axis in lung cancer and suggests that targeting CGRP could be a novel strategy to sensitize tumors to immunotherapy.

Providing broader context for this type of interaction, a perspective piece in *Science Translational Medicine* discusses the concept of treating the immune system to repair the brain in diseases like Alzheimer's [8]. The authors argue that while the immune system is initially protective in neurodegeneration, it becomes dysfunctional as the disease progresses. This has led to the development of next-generation therapeutic approaches aimed not at the brain itself, but at modulating the systemic immune response to combat neurodegenerative diseases. This conceptual framework underscores the importance of findings like the one in lung cancer, showing how interconnected these systems are.

Finally, a comprehensive review on tinnitus in *Nature Reviews Disease Primers* further illustrates this theme [1]. Tinnitus, the perception of sound without an external source, affects about 14% of adults. The review describes how its underlying mechanisms involve not just peripheral cochlear injury but also central processes like maladaptive plasticity and thalamocortical dysrhythmia. Critically, these processes are modulated by limbic and salience networks, and factors like neuroinflammation and stress can contribute to its chronicity. The condition is highly heterogeneous and often comorbid with anxiety, depression, and insomnia, reinforcing the idea that even a seemingly localized sensory symptom is deeply intertwined with systemic neuro-inflammatory and psychological processes.

Systemic Pathology and Heritable Changes Finally, we turn to studies that reveal pathology at a systemic level and uncover a surprising mechanism for how genomic changes can spread. A report in *Nature* introduces MouseMapper, a powerful new tool for studying systemic disease [3]. This is a suite of deep-learning algorithms that enables a multi-system analysis across the entire mouse body. It can automatically segment 31 different organs and tissues while also providing quantitative analysis of nerves and immune cells down to the level of fine axonal branches. Using this tool to study diet-induced obesity, the researchers identified structural alterations in specific cranial nerves associated with functional sensory deficits. MouseMapper also generated detailed 3D inflammation maps across the entire body. This framework provides a scalable approach for identifying and quantifying systemic pathologies, bridging molecular insights from animal models to human conditions.

In a discovery of fundamental biological importance, a paper in *Cell* reveals a mechanism for intercellular DNA transfer between human cells [5]. The study shows that when cells experience genomic instability from sources like radiation or mitotic poisons, fragments of nuclear DNA can end up in the cytoplasm. The researchers found that this cytoplasmic DNA can be transferred to adjacent cells through direct, contact-dependent nanotube structures. Strikingly, these transferred DNA fragments can be stably inherited and remain functional in the recipient cell, conferring new heritable traits. This uncovers a horizontal gene transfer-like mechanism in mammalian cells, suggesting a way that genomic instability could be propagated throughout a tissue, potentially reshaping genomes and contributing to disease.

Our final paper, from *PLoS Medicine*, brings the concept of systemic changes into the clinical realm of obstetrics [7]. In a large retrospective cohort study of nearly 46,000 pregnancies in the United States, researchers established new gestational-age-specific reference intervals for complete blood count indices. They then tested for associations between extreme CBC values and obstetric complications. They found that in the second trimester, specifically between 26 and 29 weeks, values for hematocrit, hemoglobin, and red cell count that were above the newly defined reference intervals were associated with about a 40 to 60 percent increased risk of a composite outcome that included hypertensive disorders of pregnancy, small for gestational age birth, and preterm birth. Furthermore, an uncommon increase in hemoglobin or red cell count between the first and second trimesters was associated with a roughly doubled risk for subsequent preterm birth. The limitation is the retrospective design. However, the findings suggest that these simple, routinely collected CBC measurements could serve as early warning signs for pregnancies at higher risk of complications, prompting closer surveillance.

Editor's Pick If you only have time for one paper this week, make it the study in *Histopathology* on using an AI-based workflow for breast core biopsies [2]. It provides a concrete, validated example of how integrating AI directly into the LIS can significantly reduce biomarker turnaround time, directly impacting patient care pathways.

Clinical Bottom Line Here are the key takeaways from this week in Pathology. First, in breast pathology, an integrated AI workflow can automatically trigger biomarker testing on high-risk biopsies, cutting turnaround time by about a day without loss of accuracy [2]. Second, for patients with chronic kidney disease, a novel urinary reporter can non-invasively detect and stage fibrosis, outperforming standard markers like creatinine and eGFR for differentiating mild versus severe disease [9]. Third, in pregnancy, be aware that second-trimester hemoglobin, hematocrit, or red cell counts above the gestational-age-specific reference range are associated with an increased risk of obstetric complications. A large increase from the first trimester is particularly concerning for preterm birth risk [7]. Fourth, in lung adenocarcinoma, sensory nerves can suppress anti-tumor immunity by inhibiting tertiary lymphoid structures. This suggests CGRP blockade as a potential new therapeutic avenue [6]. And finally, for diagnosing parkinsonian syndromes, a multimodal approach combining dermal seed amplification assays for alpha-synuclein and 4-repeat tau with serum neurofilament light chain is superior to any single biomarker [10].

That's your roundup for This Week in Pathology. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

This is an automated summary generated by artificial intelligence, which can make mistakes. Always review the original source materials.