D2-40 and CK17 Immunohistochemistry as a Diagnostic Adjunct for HPV-Independent Squamous Lesions in the Vulva and Their Role in Defining Atypical Lichen Sclerosus.

Vulvar lichen sclerosus (LS) is a common, chronic inflammatory disorder with a subset of cases progressing to differentiated vulvar intraepithelial neoplasia (dVIN) and/or squamous cell carcinoma (SCC). Histopathologic diagnosis of LS and dVIN can be challenging, and it is difficult to predict the subset of LS cases that progress. Immunohistochemistry (IHC) may be a useful diagnostic aid in this setting. CK17 has been shown to be overexpressed in invasive SCC and dVIN, and less commonly in LS. Similar to CK17, D2-40 has been correlated with cutaneous SCC prognosis but has not been evaluated in vulvar lesions. We identified a total of 13 patients with HPV-independent vulvar SCC that had precursor LS or dVIN. CK17 and D2-40 IHC stain intensity and pattern was scored in foci of LS, dVIN, and SCC. An increase in basal layer D2-40 expression was observed with progression from LS to dVIN with strong and diffuse staining in SCC. CK17 maintained similar stain intensity among squamous lesions, but displayed different patterns of staining, with superficial staining in LS, suprabasal staining in dVIN, and diffuse staining in SCC. A subset of LS cases displayed an intermediate (suprabasal) CK17 IHC profile, wild-type p53 expression, and cytomorphologic and architectural features intermediate between LS and dVIN; we defined such cases as "atypical LS." We found that a panel of D2-40/CK17 can serve as a diagnostic adjunct to differentiate LS, dVIN, and invasive SCC. Additional studies with larger patient cohorts are needed to validate these findings and determine their prognostic significance.

Unusual isolated cytomegalovirus cutaneous infections: A subtle histopathologic diagnosis with review of the literature.

Cytomegalovirus (CMV) infection is common and often self-limited. Reactivation results in a variety of disease presentations, especially in the setting of immunocompromise. While cutaneous manifestations of systemic CMV infection are rare, dermatologic manifestations of CMV are increasingly reported with a wide morphologic spectrum clinically. Three male patients, with untreated human immunodeficiency virus (HIV), penile lichenoid dermatitis treated with long-term topical and intralesional corticosteroids, and metastatic Merkel cell carcinoma on immune checkpoint inhibitor therapy, each presented with isolated cutaneous ulcers. The ulcers were located on the perianal skin, glans of the penis, and distal thumb. In each case, nonspecific histopathologic features were seen. However, very rare dermal cytomegalic cells with nuclear and cytoplasmic inclusions were present and highlighted with an immunohistochemical stain for CMV. Isolated ulcers due to CMV infection may occur in the setting of systemic or localized immunosuppression. A high index of suspicion is needed upon histopathologic evaluation, as few cytomegalic cells may be present and accurate diagnosis is crucial for prompt and appropriate clinical management.

Dematiaceous fungal infections: clinical and pathologic conundrums.

Dematiaceous fungi are defined by pigment within their cell walls. They are increasingly recognised human pathogens, causing a wide range of clinical presentations, from localised subcutaneous infections to disseminated disease in rare cases. We report our institutional experience with diagnosis of dematiaceous fungal infections from 2005 to 2022 and highlight four instructive cases that clinically and pathologically mimicked other diseases for which the diagnosis was confirmed by fungal culture (one case) or supported by PCR with 28S rRNA and internal transcribed spacer primers (three cases). Two patients were immunocompromised and two had presumed exposure to the organism. In each highlighted case, fungal infection was not clinically suspected, and the pathologist was critical in making the diagnosis and ensuring appropriate clinical management, which was supplemented by fungal stains and novel molecular methods.

Utilizing PTEN immunohistochemistry as a screening test for Cowden syndrome.

OBJECTIVES: Cowden syndrome (CS) is a multisystem disease with an elevated lifetime risk of internal malignancy. We aim to assess the role of PTEN immunostain as a screening test for CS in a variety of common CS-associated neoplasms, with a particular focus on cutaneous tumors. METHODS: We retrospectively searched for patients meeting criteria for CS and/or demonstrating germline PTEN mutation from 2008 to 2022. We then performed PTEN immunostains on tumors of these patients as well as control cases. RESULTS: Our study included 30 patients with CS who had a total of 25 CS-associated malignancies (13 thyroid, 8 breast, and 4 endometrial carcinomas). Specifically, there were 11 patients with biopsy-confirmed CS-associated cutaneous neoplasms, including 1 patient with multiple trichilemmomas and 3 with multiple sclerotic fibromas. In total, 45 CS-associated tumors (6 trichilemmomas, 7 sclerotic fibromas, 5 thyroid carcinomas, 18 adenomatous thyroid nodules, 6 breast carcinomas, and 3 endometrial carcinomas) and 31 non-CS cases (9 trichilemmomas, 5 sclerotic fibromas, 8 adenomatous thyroid nodules, and 3 thyroid, 3 breast, and 3 endometrial carcinomas) were available for PTEN immunohistochemical staining. PTEN expression was lost in 43 (96%) of 45 CS-associated lesions and retained in 30 (97%) of 31 sporadic tumors. The overall sensitivity and specificity of PTEN loss of expression as a screening test for CS were 96% and 97%, respectively. CONCLUSIONS: PTEN immunohistochemistry on CS-associated tumors, especially trichilemmomas, can serve as a readily accessible and cost-effective screening test for CS.

Sentinel lymph node assessment in melanoma: current state and future directions.

Assessment of sentinel lymph node status is an important step in the evaluation of patients with melanoma for both prognosis and therapeutic management. Pathologists have an important role in this evaluation. The methodologies have varied over time, from the evaluation of dimensions of metastatic burden to determination of the location of the tumour deposits within the lymph node to precise cell counting. However, no single method of sentinel lymph node tumour burden measurement can currently be used as a sole independent predictor of prognosis. The management approach to sentinel lymph node-positive patients has also evolved over time, with a more conservative approach recently recognised for selected cases. This review gives an overview of past and current status in the field with a glimpse into future directions based on prior experiences and clinical trials.

Clinical Next-Generation Sequencing Panels Reveal Molecular Differences Between Merkel Cell Polyomavirus-Negative Merkel Cell Carcinomas and Neuroendocrine Carcinomas.

OBJECTIVES: We aim to determine molecular differences between Merkel cell polyomavirus (MCPyV)-negative Merkel cell carcinomas (MCCs) and neuroendocrine carcinomas (NECs). METHODS: Our study included 56 MCCs (28 MCPyV negative, 28 MCPyV positive) and 106 NECs (66 small cell NECs, 21 large cell NECs, and 19 poorly differentiated NECs) submitted for clinical molecular testing. RESULTS: APC, MAP3K1, NF1, PIK3CA, RB1, ROS1, and TSC1 mutations, in addition to high tumor mutational burden and UV signature, were frequently noted in MCPyV-negative MCC in comparison to small cell NEC and all NECs analyzed, while KRAS mutations were more frequently noted in large cell NEC and all NECs analyzed. Although not sensitive, the presence of either NF1 or PIK3CA is specific for MCPyV-negative MCC. The frequencies of KEAP1, STK11, and KRAS alterations were significantly higher in large cell NEC. Fusions were detected in 6.25% (6/96) of NECs yet in none of 45 analyzed MCCs. CONCLUSIONS: High tumor mutational burden and UV signature, as well as the presence of NF1 and PIK3CA mutations, are supportive of MCPyV-negative MCC, whereas KEAP1, STK11, and KRAS mutations are supportive of NEC in the appropriate clinical context. Although rare, the presence of a gene fusion is supportive of NEC.

An Unusual Case of a Scrotal Porocarcinoma and Review of the Literature.

ABSTRACT: Porocarcinomas are rare tumors derived from the acrosyringium and eccrine ducts, which most commonly occur on the lower extremities or head and neck region in older adults. Microscopically, they invariably demonstrate continuity with the epithelium, showing downgrowth of broad anastomosing bands with more infiltrative intradermal cords and nests of pleomorphic tumor cells with ductal lumina; an associated poroma may also be seen. We report an unusual case of a porocarcinoma arising on the scrotum of a 55-year-old man. Because of the extraordinary location and the presence of keratinizing squamous differentiation, distinction from a squamous cell carcinoma was particularly challenging. Close examination revealed the presence of a co-existing poroma, and immunohistochemistry revealed loss of YAP1 with diffuse nuclear expression of NUT in both the porocarcinoma and poroma components. This finding is particularly suggestive of a YAP1::NUTM1 fusion which has been reported to be highly specific for poroid neoplasms. Distinction of porocarcinoma from its mimics is important due to the frequent aggressive behavior of this neoplasm.

Multimodality Imaging of Progressive Aortic Valve Endocarditis: From Endophthalmitis to Aorto-Atrial Fistula.

Our case highlights an atypical presentation of aortic valve endocarditis after initial presentation with endophthalmitis. This case demonstrates the rapidity of evolution of aortic valve endocarditis through sequential, multimodal imaging, and features the importance of a multidisciplinary approach required for the management of complicated aortic valve endocarditis. A male in his mid-thirties was admitted to the hospital with left endophthalmitis and diabetic ketoacidosis. He was found to have aortic valve endocarditis and severe aortic insufficiency, which progressed to aortic root pseudoaneurysm and subsequently to aorto-atrial fistula in less than 72 hours, as demonstrated by consecutive multimodality imaging studies. After extensive surgical repair, post-operative recovery, and rehabilitation, he was discharged home with a good functional outcome. Sequential and multimodal imaging can be beneficial in diagnosing paravalvular infection early in its evolution, which is crucial for decision-making regarding medical and surgical treatment strategies.

Sentinel lymph node tumour burden using digital cell count estimation predicts outcomes in melanoma.

BACKGROUND AND AIMS: Cutaneous melanoma often metastasises in primis to sentinel lymph nodes (SLNs). Currently, there is no standardized method of characterizing the micrometastatic tumour burden in SLN biopsies for melanoma. Different criteria have been developed to evaluate SLN biopsies, yet none consider the number of cells identified. Here, we used software analysis to digitally quantify metastatic tumour burden within SLNs and correlated these data with clinicopathological and prognostic information. METHODS AND RESULTS: We identified 246 cases of SLN biopsies, including 63 positive (26%) and183 (74%) negative for metastatic melanoma. Digital cell counting was performed within the greatest metastatic focus and the entire metastatic tumour burden within the same SLN. Increasing cell count in the largest metastatic deposit correlated with the previously described Rotterdam [Spearman's r = 0.91; 95% confidence interval (CI) = 0.84, 0.94], Starz (Spearman's r = 0.78; 95% CI = 0.68, 0.87) and Dewar criteria (P < 0.01), validating our method of using cell count to define SLN tumour burden. Additionally, increasing cell count was associated with decreased metastasis-free survival (hazard ratio = 2.29; 95% CI = 1.22, 4.31). CONCLUSION: These data support the use of computerized cell count analysis for prognostication of outcomes in patients undergoing SLN biopsy.

Designing and Implementing a Virtual Anatomic Pathology Elective During the COVID-19 Pandemic.

The COVID-19 pandemic transformed conventional undergraduate medical education, converting previously in-person clerkships into virtual experiences. In order to allow students to gain exposure to the field of pathology, make connections with pathologists, and provide opportunities for letters of recommendation, the authors quickly developed a Virtual Anatomic Pathology Elective at the University of Minnesota. We succeeded in developing the foundation of a Virtual Anatomic Pathology Elective that allows for the rotation to be accessible not only to our medical students but also to international medical graduates and medical students from different programs. In 1 month, we were able to create a 4-week elective that was available before the start of the 2021 residency application season. We provided students with the closest possible experience to an in-person Anatomic Pathology Elective by developing an introductory week of lectures and assignments that provided structure for the rotation, introduced the field of anatomic pathology, and demonstrated the role of pathologists in health care. Furthermore, students attended virtual resident lectures and grand rounds, participated in virtual sign-out sessions, and presented an interesting case to the faculty at the end of their rotation. The goal was ultimately to customize the curriculum to students' interests by making the rotation applicable to those applying to pathology as well as to other specialties (eg, general surgery, internal medicine, dermatology). Overall, we were able to design and implement a novel Virtual Anatomic Pathology Elective which we know can be effectively reproduced by other medical schools.

Wearable Woes: Allergens in Diabetic Devices.

Novel diabetic devices are being developed to help manage diabetes and improve the quality of life of patients with diabetes. Both insulin pumps and glucose monitors are becoming increasingly convenient, long-lasting, and discrete for patients, but this often requires the use of strong external cutaneous adhesives and increased contact time with the skin. As a consequence, these devices have been associated with a variety of dermatologic reactions, namely, irritant and allergic contact dermatitis. Some of these reactions can be severe, precluding the use of these devices, which puts patients' long-term health at risk. Herein, we review the history of diabetic devices and reported cutaneous reactions to diabetic devices and commonly cited allergens.

Isolated metastatic pancreatic adenocarcinoma to the uterine cervix: A case report.

The uterine cervix is an uncommon site of metastatic cancer. Specifically, pancreatic adenocarcinoma metastatic to the cervix is an exceptionally rarely reported phenomenon. We encountered a case of recurrent pancreatic adenocarcinoma presenting as a solitary metastasis to the cervix. To our knowledge, this is the only report describing an isolated recurrence of pancreatic adenocarcinoma to the cervix. When diagnosing metastatic disease to the cervix, it is also imperative for the clinician and pathologist to consider histologic mimics, such as the newly described gastric-type mucinous endocervical adenocarcinoma. Metastatic disease to the cervix may benefit from surgical resection.

Comparative analysis of eukaryotic cell-free expression systems.

Cell-free protein synthesis (CFPS) allows researchers to rapidly generate functional proteins independent of cell culture. Although advances in eukaryotic lysates have increased the amount of protein that can be produced, the nuances of different translation systems lead to variability in protein production. To help overcome this problem, we have compared the relative yield and template requirements for three commonly used commercial cell-free translation systems: wheat germ extract (WGE), rabbit reticulocyte lysate (RRL), and HeLa cell lysate (HCL). Our results provide a general guide for researchers interested in using cell-free translation to generate recombinant protein for biomedical applications.