About

Paul Weisman is an Associate Professor (CHS) in the Department of Pathology and Laboratory Medicine at the University of Wisconsin School of Medicine and Public Health. He completed his residency training in Anatomic Pathology at the Feinberg School of Medicine, Northwestern University, and fellowship training in Oncologic Surgical Pathology and Breast Pathology. His research interests include gynecologic cancer, with a focus on the pathology of breast and gynecologic tissues, as well as bone, soft tissue, and thoracic pathology. Dr. Weisman has contributed to the understanding of various pathological patterns in gynecologic cancers, including the immunostaining patterns in endometrial serous carcinoma and the molecular characteristics of high-grade endometrioid carcinomas. His clinical practice encompasses surgical pathology with a specialization in breast, gynecologic, bone, soft tissue, and thoracic pathology.

Research topics

• Medicine
• Chemistry
• Biology
• Pathology
• Internal medicine
• Endocrinology
• Biochemistry
• Cell biology
• Chromatography
• Anatomy

Selected publications

• Mucinous ovarian tumor characterization by p53 and HER2 classification

  Gynecologic Oncology · 2026-04-23

  article
  PublisherDOI

• HPV-associated Endocervical Adenocarcinoma In Situ (AIS) With an ER+/Vimentin+/CEA− immunophenotype Mimicking Tubo-endometrioid Metaplasia

  International Journal of Gynecological Pathology · 2025-08-05

  articleSenior authorCorresponding

  HPV-associated endocervical adenocarcinoma in situ (AIS) is typically ER-, vimentin-, and CEA+. By contrast, tubo-endometrioid metaplasia (TEM), a well-known mimicker of AIS, is typically ER+, vimentin+, and CEA-. Both AIS and TEM express p16, with block-positive expression in AIS and predominantly patchy expression in TEM; however, TEM may also exhibit p16 expression that is extensive enough that it borders on block-like expression. Here we share 2 cases of endocervical AIS that showed an endometrioid immunophenotype (ER+, vimentin+, and CEA-). The AIS in these cases also had a second population of pale p40- epithelioid cells resembling the ciliated cells of TEM; no true cilia were seen. High-risk human papillomavirus (HPV) in situ hybridization (HR-HPV ISH) testing was positive in both cases of AIS, establishing their HPV association. Despite the lack of true cilia, the morphology and immunophenotype of the AIS in these cases resulted in a very TEM-like picture. Given the aforementioned propensity of TEM to show a high degree of p16 expression, we share these cases as a reminder that an endometrioid-like immunophenotype by ER, CEA, and vimentin IHC does not unequivocally establish a benign diagnosis.

  PublisherDOI

• Estrogen Receptor (ER) and Progesterone Receptor (PR) Immunohistochemistry is Sensitive and Specific for Differentiating Retroperitoneal Leiomyosarcomas With Symplastic-like Features From Their Uterine Mimics

  International Journal of Gynecological Pathology · 2025-09-03 · 1 citations

  articleSenior author

  Previous studies have evaluated the utility of estrogen receptor (ER) and progesterone receptor (PR) immunohistochemistry (IHC) in differentiating uterine versus extrauterine leiomyosarcomas (LMS). At best, these studies have shown only modest sensitivity and specificity for these markers in this context. In our own practice, we have noticed that retroperitoneal LMS, such as those arising in the wall of the inferior vena cava, frequently exhibit a remarkable resemblance not to uterine LMS, but rather to uterine leiomyomas (LM) with bizarre nuclei, formerly known as symplastic LM. This includes areas with bland nuclear cytology, punctuated by the presence of cells with large bizarre nuclei but a paradoxically low mitotic index. We refer to these areas in retroperitoneal LMS as "symplastic-like." It has been our experience that these "symplastic-like" areas are frequently the predominant or exclusive component in small core biopsies of retroperitoneal LMS, even when the resection of these tumors reveals the presence of more conventional high-grade LMS morphology. In female patients, symplastic-like morphology in a smooth muscle tumor at an intra-abdominal site raises the possibility of iatrogenic dissemination of a uterine LM with bizarre nuclei from a prior myomectomy or morcellation procedure. We hypothesized that negative staining for ER and PR by IHC could effectively exclude a uterine origin, given the high sensitivity of these markers for all variants of uterine LM. After successfully using ER and PR IHC in our clinical practice on a few index cases, we decided to study a larger cohort of carefully selected cases to systematically determine the sensitivity and specificity of these markers in this very specific context. Confining our search to include only female patients, we identified 8 cases of retroperitoneal LMS that had been confirmed radiologically, intraoperatively and/or histologically to originate from a retroperitoneal source and 6 cases of uterine-based LM with bizarre nuclei, all diagnosed at our institution over an 8-year period. We tested only whole slides for ER and PR IHC. ER and PR were both completely negative in all 8 cases of retroperitoneal LMS and were both strongly expressed in all 6 cases of LM with bizarre nuclei. In conclusion, despite conflicting data in the literature regarding the utility of ER and PR in distinguishing uterine versus extrauterine smooth muscle tumors, we endorse the use of these markers for the specific distinction of retroperitoneal LMS with symplastic-like features from disseminated uterine LM with bizarre nuclei in female patients.

  PublisherDOI

• 91 Novel Low-Grade Fibroblastic Neoplasm with Co-Expression of MUC4 and Beta-catenin: Clinicopathologic and Molecular Characterization of Eight Cases

  Laboratory Investigation · 2025-03-01 · 3 citations

  articleOpen access
  PublisherOA PDFDOI

• Microcystic Adnexal Carcinoma (MAC) and Eccrine Cutaneous Mixed Tumor (ECMT): 2 Cases of Rare HPV-independent Vulvar Cutaneous Adnexal Tumors

  International Journal of Gynecological Pathology · 2025-05-08

  articleCorresponding

  Microcystic adnexal carcinoma (MAC) and eccrine cutaneous mixed tumor (ECMT) are both cutaneous adnexal tumors that may occur in the vulvar region, but are very rare at this site. Consequently, they may not enter the differential diagnosis of vulvar lesions for gynecologic pathologists in a subspecialized practice setting. Here we report a case of MAC and a case of ECMT recently diagnosed at our institution and underscore key histologic and immunophenotypic features of each lesion that can assist in their correct identification. Both MAC and ECMT have a tubular to corded pattern of lesional cells within a desmoplastic to chondromyxoid stroma. However, MAC shows true eccrine sweat duct differentiation, characterized by 2 SOX10 negative cell layers, including an outer p63+/p40+/EMA- basal cell layer and an inner p63-/p40-/EMA+ ductal layer. The main differential diagnostic considerations for vulvar MAC include other cutaneous adnexal tumors with true eccrine sweat duct differentiation, namely syringoma and squamoid eccrine ductal carcinoma (SEDC). Conversely, ECMT is characterized by a single SOX10+ cell population without immunoreactivity for p63 or p40. The main differential diagnostic considerations for ECMT include the apocrine variant of cutaneous mixed tumor (ACMT)-the cutaneous analog of salivary gland pleomorphic adenoma-and other SOX10+ salivary gland-type neoplasms. Unlike the recently described vulvar analog of HPV-associated multiphenotypic sinonasal carcinoma, neither MAC nor ECMT are HPV-associated and both are therefore p16 negative. In summary, we report one case each of vulvar MAC and ECMT and discuss the key histologic features and ancillary testing results that can help to differentiate these lesions from their morphologic mimics.

  PublisherDOI

• 505 Re-envisioning the Rotating Medical Student Anatomic Pathology Educational Experience

  Laboratory Investigation · 2025-03-01

  articleOpen access
  PublisherOA PDFDOI

• Appendix-like morphology in primary ovarian mucinous tumors lacking a concurrent mature teratoma: A series of 4 cases illustrating the utility of STR analysis

  Annals of Diagnostic Pathology · 2025-07-15 · 1 citations

  articleCorresponding
  PublisherDOI

• A Case of CDKN2C/CIC Null Epithelioid Leiomyosarcoma With a Low-grade Component Indistinguishable From Leiomyoma

  International Journal of Gynecological Pathology · 2025-05-08 · 1 citations

  articleSenior author

  Numerous emerging molecularly defined subtypes of uterine leiomyosarcoma (LMS) have been described in recent years. Here we report our experience with a challenging case of the recently described CDKN2C/CIC null subtype of LMS - a LMS subtype that is frequently epithelioid in appearance, is wild-type for both TP53 and RB1 and may exhibit low-grade histology that falls short of LMS. The 48-year-old patient was initially diagnosed with an epithelioid leiomyoma with a component of intravenous leiomyomatosis. Recurrence occurred 5 years later with an extensive disease burden in the abdomen and pelvis. Upon review, the lesion in the hysterectomy specimen and the recurrent tumor had similar morphology. This included (1) focal epithelioid morphology meeting current diagnostic criteria for epithelioid LMS and (2) other areas with morphology indistinguishable from leiomyoma (LM), including conventional spindle cell LM, cellular LM, and LM with bizarre nuclei. Targeted next-generation molecular analysis performed on both the original tumor in the hysterectomy specimen and the tumor from the recurrence showed the same CDKN2C/CIC null profile. This case highlights the striking intratumoral heterogeneity that is possible in CDKN2C/CIC null LMS, including areas morphologically indistinguishable from LM. Clinicopathological findings in this case, including features that may assist in recognizing this challenging LMS subtype, are discussed. We underscore the importance of early diagnosis, which can facilitate appropriate adjuvant and/or maintenance therapy that may decrease the morbidity associated with extensive debulking surgery.

  PublisherDOI

• Immunohistochemistry as an adjunct for challenging histological patterns of borderline Brenner tumors: An illustrative study of 4 cases

  Annals of Diagnostic Pathology · 2024-05-08 · 1 citations

  articleSenior authorCorresponding
  PublisherDOI

• Morphologic Spectrum of HPV-associated Sinonasal Carcinomas

  Head and Neck Pathology · 2024-08-05 · 6 citations

  articleOpen access
  PublisherOA PDFDOI

Frequent coauthors

• Stephanie M. McGregor

  University of Wisconsin Carbone Cancer Center

  42 shared

• Jin Xu

  Zhuhai People's Hospital

  33 shared

• Pamela K. Kreeger

  University of Wisconsin–Madison

  30 shared

• Ahmed Al‐Niaimi

  22 shared

• Alain Cagaanan

  Englewood Hospital and Medical Center

  20 shared

• Kay J. Park

  19 shared

• Christopher Flynn

  Rice University

  18 shared

• Pei Hui

  17 shared