About

Morgan Angus Darrow, M.D., is an Assistant Professor in the Department of Pathology and Laboratory Medicine at UC Davis Health. His clinical interests include general surgical pathology, bone and soft tissue pathology, and resident education. His research focuses on tumor immune microenvironments, novel imaging techniques, digital pathology applications, and treatment strategies for bone and soft tissue sarcomas. Dr. Darrow completed his undergraduate studies with a B.S. in Biology from West Virginia University in 2007 and earned his M.D. from West Virginia University School of Medicine in 2011. He completed his residency in Anatomic and Clinical Pathology at West Virginia University and a fellowship in Surgical Pathology at UC Davis Medical Center. Recognized for his professionalism and teaching, he received the Faculty Professionalism Award in 2017 and the UC Davis Pathology Residency Program Teaching Award in 2016.

Research topics

• Medicine
• Internal medicine
• Pathology
• Radiology
• Immunology
• Artificial Intelligence
• Computer Science
• Cancer research
• Biology
• Surgery
• Genetics
• Nuclear medicine
• Medical physics
• Cell biology

Selected publications

• Genomic Landscape of Myoepithelial Carcinoma Tumors

  Oral Diseases · 2026-03-15

  article

  OBJECTIVE(S): Myoepithelial Carcinoma (MECA) is an ultra-rare soft tissue cancer with a rare EWSR1::KLF15 fusion reported in some cases. However, fusion positive MECA has been classified as a carcinoma, despite sharing qualities with sarcomas in terms of fusion protein rearrangement. An exploration of MECA in the context of a sarcoma versus an adenocarcinoma could be crucial to the understanding of MECA with respect to other cancers. Beyond gene fusions, MECA can also be difficult to characterize, but functional genomics could reveal distinctions. SUBJECT(S) (OR MATERIALS) AND METHODS: We performed next generation DNA exome and RNA deep sequencing for a 27 patient cohort for this ultra-rare cancer. RESULTS: Our Principal Component Analysis that categorized MECA tumors among other sarcomas vs. salivary carcinomas, with closest relatedness to salivary Adenoid Cystic Carcinoma. Both fusion positive and fusion negative MECA over-express IGF1R. CONCLUSION(S): Despite sharing a chromosomal translocation partner (the EWSR1 gene) with sarcomas, MECA are most related to other salivary carcinomas. Further exploration of IGF1R as a therapeutic target in MECA is warranted. We also make available the 27 patients' next generation DNA exome and RNA sequencing through the EGA Repository.

  PublisherDOI

• Core Needle Biopsy of the Abdominal Fat Pad for Diagnosis of Amyloidosis

  Ultrasound Quarterly · 2026-01-29

  article

  Amyloidosis is a rare systemic disorder that is underdiagnosed and whose incidence is increasing as the population ages. The reference standard for diagnosis is endomyocardial biopsy, though its utility as a screening tool is limited. Fine needle aspiration (FNA) and surgical excisional biopsy (SEB) of the abdominal fat pad have emerged as alternatives to endomyocardial biopsy as screening tools for amyloidosis. Given concerns about the variable sensitivity of FNA and the more invasive nature of SEB, our referring providers asked our group to perform core needle biopsies (CNB) of the abdominal fat pad. While limited prior work has reviewed the performance of fat pad CNB, the technical details of this procedure have not been described in the literature. With this technical note, we hope to encourage more radiologists to offer ultrasound-guided CNB of the abdominal fat pad as an additional procedure in the toolkit of interventional radiologists.

  PublisherDOI

• Fibroadenoma arising in axillary ectopic breast tissue in an adolescent female: A case report

  Journal of Pediatric Surgery Case Reports · 2025-06-03 · 1 citations

  articleOpen accessSenior author
  PublisherDOI

• Isolated tuberculous osteomyelitis of the wrist: A case report

  Radiology Case Reports · 2025-11-23

  articleOpen access

  (MTB) involving any organ besides the lungs. Rarely, tuberculosis (TB) can infect the bones and joints, which accounts for only 1%-5% of total TB cases in Europe and the United States. In this case report, we present a 29-year-old man with history of gout who presented with chronic left wrist pain. Imaging demonstrated synovitis and erosive arthritis of the distal radius, ulna, and carpal bones. An initial synovial biopsy showed granulomatous inflammation but mycobacteria were not detected by microscopic examination or broad-spectrum polymerase chain reaction (PCR). Seven months later, a repeat bone biopsy showed TB osteomyelitis. The patient was then treated with anti-tuberculous therapy. Notably, imaging findings included the "penumbra sign," a highly specific feature seen on magnetic resonance imaging for subacute osteomyelitis. This case illustrates the challenges in diagnosing extrapulmonary TB osteomyelitis.

  PublisherDOI

• Author response for "Genomic Landscape of Myoepithelial Carcinoma Tumors"

  2025-11-18

  peer-review
  PublisherDOI

• A Multicenter Study to Evaluate Diagnostic Accuracy by Pathologists Using the Aperio GT 450 DX in Local and Remote Viewing Stations

  Archives of Pathology & Laboratory Medicine · 2025-02-13 · 1 citations

  articleOpen access

  CONTEXT.—: The adoption of digital pathology may enable pathologists to perform primary diagnosis in both local and remote whole slide image viewing settings, improving logistics and convenience. OBJECTIVE.—: To test the performance of a new whole slide imaging system (Aperio GT 450 DX), both local intranet-based and remote internet-based viewing were compared with manual glass slide light microscopy. DESIGN.—: A total of 1161 curated cases, enriched with difficult clinical diagnoses, were enrolled in this accuracy study and digitally scanned on 3 Aperio GT 450 DX instruments at 3 clinical sites. Ten reading pathologists across the 3 study sites viewed images either locally (directly connected to the image server) or remotely (viewed over an internet connection). Each diagnosis was scored (concordant, minor discrepancy, or major discrepancy) by a separate team of 3 adjudication pathologists. The diagnostic accuracy of the Aperio GT 450 DX was tested by comparing the whole slide image review diagnosis with the conventional light microscope manual slide review diagnosis. RESULTS.—: The difference in the major discrepancy rate between whole slide image review diagnosis and manual slide review diagnosis was 2.40% (95% CI, 1.40%-3.39%), meeting the predefined acceptance criterion of the 95% CI upper bound of 4% or less. Secondary end points were also met, including an upper bound of 7% or less and both local-only and remote-only upper-bound discrepancy rates of 4% or less. Major discrepancies were slightly lower for the remotely viewed cases (2.17%) compared with local direct server connection (2.61%), and time per read was not different. CONCLUSIONS.—: The diagnoses made using the Aperio GT 450 DX, using both local and remote access image data, were noninferior to the diagnoses made using conventional light microscopy.

  PublisherDOI

• MRI of atypical lipomatous tumor: does contrast help? A multicenter study

  Skeletal Radiology · 2025-06-05 · 2 citations

  articleOpen access

  OBJECTIVE: To compare the diagnostic performance of non-contrast MRI versus MRI with contrast for differentiating atypical lipomatous tumors (ALT) from lipomas. MATERIALS AND METHODS: This multicenter retrospective study included subjects with a histopathologic diagnosis of lipoma or ALT and a preoperative MRI study with contrast. An experienced musculoskeletal radiologist reviewed the images in two sessions, the first session with non-contrast only, and the second session, including postcontrast sequences. In each session, the radiologist assigned a binary classification (lipoma or ALT) and a 5-point diagnostic score to reflect clinical reporting. Pathology reports served as the reference standard. McNemar's test was used to evaluate the statistical significance of the differences in sensitivity and specificity, while intraclass correlation coefficients (ICC) compared ordinal diagnostic scores. RESULTS: Four-hundred and forty-one patients (219 ALT, 222 lipoma) were eligible for analysis. In the first session, 76.1% of the lesions were classified as true negative and 76.3% as true positive. In the second session, 74.8% of lesions were assessed as true negative and 77.2% as true positive. There were no significant differences between the two readings in terms of sensitivity or specificity. The agreement in assigning the exact score between the two sessions, as measured by ICC, was 0.878 (95%CI: 0.855-0.898). CONCLUSION: Our study found no significant difference between the radiological readings of MRIs that used only precontrast sequences were used for the evaluation of lipoma and ALT, and those that included both pre- and postcontrast-enhanced sequences.

  PublisherOA PDFDOI

• Deep-learning enabled classification of HER2 score in breast cancer using pyramid sampling

  2025-03-19

  article

  We introduce a deep learning-based approach utilizing pyramid sampling to automate HER2 (human epidermal growth factor receptor 2) status classification in immunohistochemically (IHC) stained breast cancer tissue images. Our method uses pyramid sampling to analyze features at multiple spatial scales, addressing HER2 expression heterogeneity by capturing both detailed cellular features and broader tissue architecture. Our model is trained and validated on tissue microarray samples with 2,274 cores, where the ground truth is rigorously established by board-certified pathologists. Tested on a dataset of 523 core images from 300 distinct patients, the model achieved a classification accuracy of 85.47% across four classes (0/1+/2+3+) using a voting-based protocol with different random samplings. The high accuracy and stability of this approach demonstrate its ability to effectively handle staining variability and tissue heterogeneity, positioning it as a reliable second opinion tool to assist diagnosis in pathology departments.

  PublisherDOI

• Data from Genetic Screen in a Preclinical Model of Sarcoma Development Defines Drivers and Therapeutic Vulnerabilities

  2024-11-01

  preprintOpen access

  <div>AbstractPurpose:<p>High-grade complex karyotype sarcomas are a heterogeneous group of tumors with a uniformly poor prognosis. Within complex karyotype sarcomas, there are innumerable genetic changes but identifying those that are clinically relevant has been challenging.</p>Experimental Design:<p>To address this, we utilized a pooled genetic screening approach, informed by The Cancer Genome Atlas (TCGA) data, to identify key drivers and modifiers of sarcoma development that were validated <i>in vivo</i>.</p>Results:<p><i>YAP1</i> and wild-type <i>KRAS</i> were validated as drivers and transformed human mesenchymal stem cells into two distinct sarcoma subtypes, undifferentiated pleomorphic sarcoma and myxofibrosarcoma, respectively. A subset of tumors driven by <i>CDK4</i> and <i>PIK3CA</i> reflected leiomyosarcoma and osteosarcoma demonstrating the plasticity of this approach and the potential to investigate sarcoma subtype heterogeneity. All generated tumors histologically reflected human sarcomas and had increased aneuploidy as compared to simple karyotype sarcomas. Comparing differential gene expression of TCGA samples to model data identified increased oxidative phosphorylation signaling in <i>YAP1</i> tumors. Treatment of a panel of soft tissue sarcomas with a combination of YAP1 and oxidative phosphorylation inhibitors led to significantly decreased viability.</p>Conclusions:<p>Transcriptional co-analysis of TCGA patient samples to <i>YAP1</i> and <i>KRAS</i> model tumors supports that these sarcoma subtypes lie along a spectrum of disease and adds guidance for further transcriptome-based refinement of sarcoma subtyping. This approach can be used to begin to understand pathways and mechanisms driving human sarcoma development, the relationship between sarcoma subtypes, and to identify and validate new therapeutic vulnerabilities for this aggressive and heterogeneous disease.</p></div>

  PublisherDOI

• Supplementary Figure S6 from Genetic Screen in a Preclinical Model of Sarcoma Development Defines Drivers and Therapeutic Vulnerabilities

  2024-11-01

  preprintOpen access

  <p>Additional Analysis of TCGA Data.</p>

  PublisherOA PDFDOI

Frequent coauthors

• Robert J. Canter

  University of California, Davis

  37 shared

• Steven W. Thorpe

  36 shared

• R. Lor Randall

  UC Davis Health System

  28 shared

• Sean J. Judge

  Memorial Sloan Kettering Cancer Center

  26 shared

• Janai R. Carr

  19 shared

• Edmond F. O’Donnell

  17 shared

• Kermit L. Carraway

  15 shared

• Maria Muñoz

  Eli Lilly (United States)

  15 shared

Labs

• Department of Pathology and Laboratory MedicinePI

Awards & honors

• Faculty Professionalism Award, UC Davis Department of Pathol…
• Fellow Teaching Award, UC Davis Pathology Residency Program,…