Maggie Mei-Kei Lam

All Publications

• HER2 In Situ Hybridization: Validation and Implementation of Brightfield Assay in a US Academic Pathology Laboratory. Applied immunohistochemistry & molecular morphology : AIMM Troxell, M. L., Dussaq, A. M., Solarewicz, J., Salisbury, T., Young, K., Hsu, N., Hammer, P., Karakas, C., Ollila, E., Zhang, X., Lam, M. M., Ernst, K., West, R. B., Allison, K. H., Bean, G. R. 2026

  Abstract

  Assessment of HER2 overexpression and gene (ERBB2) amplification remains an essential predictive test that determines tailored breast cancer therapy. Based on institutional needs, we recently validated the VENTANA HER2 Dual ISH DNA Probe Cocktail assay (DISH). Validation included testing 61 retrospective breast cancers, followed by 40 prospective cases (parallel testing). There was 99% concordance for binary positive/negative status when correlated with immunohistochemistry, and 87% concordance for exact ISH category (groups 1 to 5). We designed an online tool for automatic calculation of ratios and group assignment, with prompts for additional counting when needed. During the first year, 1286 DISH assays were performed, with 2.9% initial assay failures requiring repeat. Based on conservative guidelines in the first year, we sent confirmatory fluorescence in situ hybridization (FISH) in 4% of cases; 9 cases (0.7%) had discordant DISH and FISH results, all of which were near a threshold (including "low amplified" results with HER2/CEP17 ≥2, average HER2/cell 4 to 6). The average turnaround time for HER2 DISH from ordering to finalization was 3.0 days, versus 4.8 days for FISH at our institution (37.5% improvement). We encountered occasional pitfalls, including zones lacking hybridization signals, and enhanced silver dust associated with anthracosis or tattoo pigment. We also observed differences across whole slide scanner platforms. HER2 DISH advantages included the ability of pathologists to directly score slides in correlation with morphology and immunohistochemistry, improved turnaround time, and greater automation for high-volume HER2 testing, as compared with FISH. In summary, we found HER2 DISH to be an accurate and practical alternative.

  View details for DOI 10.1097/PAI.0000000000001328

  View details for PubMedID 42273884

• Reporting of both positive and negative concordance is necessary to recognise and investigate bias in digital algorithms. Journal of clinical pathology Troxell, M. L., Karakas, C., Lam, M. M., Dussaq, A. M., Bean, G., Allison, K. H. 2026

  View details for DOI 10.1136/jcp-2026-210804

  View details for PubMedID 42167914

• Integrated multiomic atlas of pancreatic solid pseudopapillary neoplasms suggests acinar cells as a potential cell-of-origin Reddy, B., Korah, M., Agolia, J. P., Reveron-Thornton, R., Lam, M., Foster, D., Longaker, M. T., Delitto, D. AMER ASSOC CANCER RESEARCH. 2026

  View details for DOI 10.1158/1538-7445.AM2026-6202

  View details for Web of Science ID 001734397100026

• Mammary small cell neuroendocrine carcinomas that showed excellent pathologic response following etoposide-based neoadjuvant chemotherapy. Breast cancer research and treatment Hammer, P. M., Enamandram, S., Ikeda, D. M., Lam, M. M., Wapnir, I. L., Chamberlain, E. D., Shaheen, S., Caswell-Jin, J. L., Itakura, H., Bean, G. R. 2025; 215 (1): 10

  Abstract

  Small cell neuroendocrine carcinoma (SCNEC) is a very rare, highly aggressive subtype of breast cancer. There are no standard recommendations for the management of mammary SCNEC, and the use and response to neoadjuvant chemotherapy are not well studied. Etoposide is an agent not included in guidelines for the management of breast cancer but traditionally used in the treatment of small cell carcinoma of the lung.We searched for institutional and consultation cases of breast SCNEC and identified those treated with neoadjuvant chemotherapy. Clinical, pathologic, and genetic findings of two patients with SCNEC of the breast treated with etoposide are described. Additionally, we performed a literature review of all known cases of mammary SCNEC treated with neoadjuvant chemotherapy to date.These two women were the sole patients who underwent neoadjuvant etoposide-based chemotherapy followed by surgery for breast SCNEC at our institution in the past 25 years. Both patients achieved excellent imaging and pathologic responses, with no evidence of residual carcinoma in the subsequent breast excisions.Etoposide may be considered as a therapeutic option in the neoadjuvant setting of breast SCNEC. More reports on this very rare breast cancer subtype and response to treatment are needed.

  View details for DOI 10.1007/s10549-025-07854-9

  View details for PubMedID 41269341

  View details for PubMedCentralID 9514991

• Classification of Invasive Lobular Carcinoma. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Troxell, M. L., Allison, K. H., Ernst, K., Lam, M. M., Bean, G. R. 2025; 38 (6): 100758

  View details for DOI 10.1016/j.modpat.2025.100758

  View details for PubMedID 40541386

• Pancreas cystic lesion with surprise findings on confocal laser endomicroscopy. VideoGIE : an official video journal of the American Society for Gastrointestinal Endoscopy Matar, A., Charville, G., Lam, M., El-Dika, S. 2025; 10 (6): 299-301

  Abstract

  The incidental diagnosis of pancreatic cystic lesions has been increasing, ranging from 2% to 45%, as determined by computed tomography or magnetic resonance imaging. This report describes the case of a 74-year-old female patient referred for a finding on magnetic resonance imaging of a unilocular cystic lesion in the pancreas tail.Based on the cyst's size and its unclear nature, the patient was subjected to a repeat EUS at our institution, which showed an anechoic 35 × 20-mm finely septated lesion in the pancreatic tail. To help determine the nature of the cyst, EUS-guided needle-based confocal laser endomicroscopy (EUS-nCLE) was used because of its ability to visualize the cyst wall mucosal layer to a micrometer resolution.EUS-nCLE of the cyst wall showed an intersecting network of vessels, with background arrangement of gray oval structures and at times background arrangement of dark lobular structures. The findings were not consistent with a mucinous pancreas cyst, serous cystadenoma, or cystic neuroendocrine tumor. As for the NGS, the cyst fluid was positive for both KRAS and PIK3CA pathogenic mutations. After the patient's distal pancreatectomy, histologic examination of the lesion entirely revealed a vascular malformation. The lesion did not have a distinct wall and was surrounded by fat and pancreas tissue. This vascular malformation is a form of lymphangioma.Lymphangiomas of the pancreas are rare, accounting for 0.2% of all pancreatic lesions. Targeted NGS performed at our institution on the surgical specimen showed absence of KRAS and PIK3CA mutations, suggesting an erroneous or false-positive initial analysis of the cyst fluid. The gray oval structures observed during EUS-nCLE correspond to adipocytes marking part of the cyst border. The dark lobular structures (coffee beans) observed during EUS-nCLE correspond to pancreatic acini marking another part of the cyst border. When these EUS-nCLE patterns are observed in a pancreas cystic lesion in the absence of any epithelial pattern, close follow-up with cross-sectional imaging should be considered instead, especially if the lesion is in a pancreas location that entails major surgery.

  View details for DOI 10.1016/j.vgie.2025.02.005

  View details for PubMedID 40496486

  View details for PubMedCentralID PMC12146039