Pathologic Features of Primary Pancreatic Malignancies.

This chapter explores the pathologic features of benign and malignant lesions of the pancreas. As pathologic classifications evolve particularly for cystic lesions and neuroendocrine tumors, it is important for physicians who treat patients with gastrointestinal malignance to fully evaluate these pathologic classifications.

Paclitaxel-induced dorsal hand-foot syndrome.

Hand-foot syndrome (HFS), also known as palmoplantar erythrodysesthesia or acral erythema, is a known adverse effect of chemotherapeutic agents that most commonly presents as palmoplantar dysesthesia and erythematous plaques localized to the palms and soles. Paclitaxel is an uncommon cause of HFS and is notable for its unique presentation on the dorsal hands and feet. We present an unusual case of paclitaxel-induced HFS localized to the dorsal hands of a 66-year-old man with metastatic angiosarcoma. Early identification and management of HFS is critical to allow for continuation of chemotherapy while improving patient quality of life.

Recurrent episodes of palpable migratory arciform erythema associated with IVIg infusions.

Palpable migratory arciform erythema (PMAE) is an uncommon T cell pseudolymphoma characterized by erythematous, annular-to-arciform papules and plaques. Although the eruption is self-limited in most cases, recurrences are routine. Diagnosis requires attention to clinical history as well as histopathologic analysis, which allow for differentiation from other T cell pseudolymphomas and gyrate erythemas. A common triggering factor has not been identified. We report a 60-year-old man who developed PMAE after IVIg infusion. Interestingly, although the individual eruptions were self-limited and resolved after several weeks, subsequent infusions predictably resulted in recurrence of PMAE, confirming the association. To our knowledge, this is the first reported case of recurrent PMAE in association with IVIg infusions.

BRCA1-associated protein (BAP1)-inactivated melanocytic tumors.

Although discussed using variable terminology, cutaneous BRCA1-associated protein (BAP1)-inactivated melanocytic tumor (BIMT) has been considered a discrete diagnostic entity since 2011. Here, we review the initial genomic studies that identified these distinct melanocytic tumors and the clinical and histopathological features that define these tumors. These epithelioid, predominantly dermal, and melanocytic tumors present as erythematous nodules and histopathologically have features that may overlap with Spitz nevi and nevoid melanoma. There is no sex predilection, and cutaneous BIMTs can appear at any age; however, in most familial (germline mutant) cases patients have multiple cutaneous tumors with a first diagnosis in the second or third decade of life; ocular melanoma and other tumors are increasingly identified in these kindreds with germline BAP1 mutation. These tumors have been described with a myriad of terms including: Wiesner nevus, nevoid melanoma-like melanocytic proliferation (NEMMP), BAP1 mutant Spitz nevus, BAP1 mutant nevoid melanoma, cutaneous BAPoma, and most recently cutaneous BIMT.

Endometriosis of the Eyelid, an Extraordinary Extra-abdominal Location Highlighting the Spectrum of Disease.

Cutaneous endometriosis is an uncommon dermatologic disorder predominantly seen in young women. Most commonly, it presents within a region of a previous surgical scar, often in relation to a gynecologic procedure on the abdomen or in close proximity to the umbilicus. The typical clinical presentation is that of papules or nodules with monthly cyclical pain and size variation. Histologically, the lesions are composed of endometrial stroma and glands. The pathophysiology is not well understood but is believed to be due to metastasis or seeding of endometrial cells. When this uncommon disorder occurs outside of the most typical clinical setting, it may cause some diagnostic difficulty. In this report, we present the first known case of cutaneous endometriosis on the eyelid.

Insulinoma-associated 1: A novel nuclear marker in Merkel cell carcinoma (cutaneous neuroendocrine carcinoma).

Merkel cell carcinoma (MCC) is a rare, clinically aggressive, cutaneous neuroendocrine (NE) neoplasm. As a tumor with small, round, blue cells, the histologic differential diagnosis for MCC can include melanoma, metastatic small cell carcinoma (SCC), nodular hematopoietic tumors, basal cell carcinoma (BCC), atypical variants of squamous carcinoma and the uncommon occurrence of primary cutaneous Ewing sarcoma. In cases with atypical histology or without the classic immunophenotype, the diagnosis can be challenging. Ultimately, immunohistochemistry (IHC) is essential to the definitive diagnosis of MCC and in difficult cases, the diagnosis may hinge entirely on the immunophenotype of the tumor cells. Insulinoma-associated 1 (INSM1) is a transcription factor expressed in tissues undergoing terminal NE differentiation. As a nuclear protein tied to both differentiation and the cell cycle, INSM1 may offer additional utility in comparison to traditional, cytoplasmic markers of NE differentiation.

#InSituPathologists: how the #USCAP2015 meeting went viral on Twitter and founded the social media movement for the United States and Canadian Academy of Pathology.

Professional medical conferences over the past five years have seen an enormous increase in the use of Twitter in real-time, also known as "live-tweeting". At the United States and Canadian Academy of Pathology (USCAP) 2015 annual meeting, 24 attendees (the authors) volunteered to participate in a live-tweet group, the #InSituPathologists. This group, along with other attendees, kept the world updated via Twitter about the happenings at the annual meeting. There were 6,524 #USCAP2015 tweets made by 662 individual Twitter users; these generated 5,869,323 unique impressions (potential tweet-views) over a 13-day time span encompassing the dates of the annual meeting. Herein we document the successful implementation of the first official USCAP annual meeting live-tweet group, including the pros/cons of live-tweeting and other experiences of the original #InSituPathologists group members. No prior peer-reviewed publications to our knowledge have described in depth the use of an organized group to "live-tweet" a pathology meeting. We believe our group to be the first of its kind in the field of pathology.

Pathologic Features of Primary Pancreatic Malignancies.

This chapter explores the pathologic features of benign and malignant lesions of the pancreas. As pathologic classifications evolve, particularly for cystic lesions and neuroendocrine tumors, it is important for physicians who treat patients with pancreatic neoplasms to fully evaluate these pathologic classifications.

Infectious Endocarditis Accompanied by Leukocytoclastic Vasculitis.

Bacterial endocarditis is a rare infection that can present with variable clinical manifestations. Rarely, it can present as cutaneous vasculitis characterized by a purpuric rash mimicking immune-mediated vasculitis. There have been a few case reports of leukocytoclastic vasculitis (LCV) due to infectious endocarditis. It is important to recognize endocarditis as a potential cause of vasculitis because treatment with immunosuppressive agents can have devastating consequences. We report a case of a 53-year-old male with endocarditis who developed a palpable purpura of the bilateral lower extremities. A skin biopsy was performed, and histopathologic and immunofluorescence studies demonstrated LCV.

Expression of angiopoietin-TIE system components in angiosarcoma.

Angiosarcoma is an aggressive malignancy of endothelial differentiation. Potential roles of the endothelial angiopoietin-tunica interna endothelial cell kinase (ANGPT-TIE) system in angiosarcoma diagnosis, pathogenesis, prognosis and treatment are undefined. To examine the expression and prognostic significance of angiopoietin-1, angiopoietin-2, TIE1 and TEK (TIE2) proteins in angiosarcoma, we immunohistochemically evaluated clinically annotated human angiosarcoma samples. Correlations of protein expression with overall survival and pathological features were explored. The cohort included 51 patients diagnosed with angiosarcoma at the age of 30-86 years (median 67). The 5-year overall survival was 45% with a median of 26 months. Moderate to strong expression of angiopoietin-1, TIE1 and TEK (TIE2) was identified in the majority of angiosarcomas and moderate to strong expression of angiopoietin-2 was observed in 42% of angiosarcomas. Increased angiopoietin-1 expression correlated with improved survival. Non-significant trends toward longer survival were also observed with increased TIE1 and TEK (TIE2) expression. Increased expression of angiopoietin-2, TIE1 and TEK (TIE2) was associated with vasoformative architecture. No differences in expression of these proteins were observed when patients were segregated by age, gender, presence or absence of metastases at diagnosis, primary tumor location, radiation association or the presence of necrosis. We conclude that components of the ANGPT-TIE system are commonly expressed in angiosarcomas. Reduced expression of these proteins is associated with non-vasoformative and clinically more aggressive lesions.

Expression of epithelial-mesenchymal transition regulators SNAI2 and TWIST1 in thyroid carcinomas.

Epithelial-mesenchymal transition is an important mechanism of epithelial tumor progression, local invasion and metastasis. The E-cadherin (CDH1) repressor SLUG (SNAI2) and the basic helix-loop-helix transcription factor TWIST1 inhibit CDH1 expression in poorly differentiated malignancies as inducers of epithelial-mesenchymal transition. Epithelial-mesenchymal transition has been implicated in progression from well to poorly differentiated/anaplastic thyroid carcinoma but the expression of SNAI2 and TWIST1 proteins and their phenotypic association in human thyroid cancers has not been extensively studied. We examined the expression of SNAI2, TWIST1 and CDH1 by immunohistochemistry in a panel of well-differentiated and anaplastic thyroid cancers and by qRT-PCR in thyroid cell lines. Ten normal thyroids, 33 follicular adenomas, 56 papillary thyroid carcinomas including 28 follicular variants, 27 follicular carcinomas and 10 anaplastic thyroid carcinomas were assembled on a tissue microarray and immunostained for SNAI2, TWIST1 and CDH1. Most (8/10) anaplastic thyroid carcinomas demonstrated strong nuclear immunoreactivity for SNAI2 with associated absence of CDH1 in 6/8 cases (75%). TWIST1 was expressed in 5/10 anaplastic thyroid carcinomas with absence of CDH1 in 3/5 (60%) cases. These findings were confirmed in whole sections of all anaplastic thyroid carcinomas and in a separate validation set of 10 additional anaplastic thyroid carcinomas. All normal thyroids, follicular adenomas, papillary and follicular thyroid carcinomas were negative for SNAI2 and TWIST1 (P<0.0001) and all showed strong diffuse immunoreactivity for CDH1 (P=0.026). Expression of SNAI2, TWIST1 and CDH1 mRNA varied in a normal thyroid, papillary carcinoma and two anaplastic thyroid carcinoma cell lines tested, but the highest levels of CDH1 mRNA were detected in the normal thyroid cell line while the anaplastic thyroid carcinoma cell line demonstrated the highest levels of SNAI2 and TWIST1 mRNA. Our findings support the role of epithelial-mesenchymal transition in the development of anaplastic thyroid carcinoma.

Squamoid Eccrine Ductal Carcinoma.

Squamoid eccrine ductal carcinoma (SEDC) is a rare and under-recognized primary cutaneous tumor with a high risk for local recurrence and metastasis. The tumor has a biphasic histologic appearance consisting of a superficial portion indistinguishable from squamous cell carcinoma (SCC) and a deeper component demonstrating eccrine ductal differentiation. Because of superficial sampling, SEDC often is misdiagnosed as SCC during the initial biopsy. The diagnosis usually is made during complete excision when deeper tissue is sampled. Confirmation of the diagnosis can be achieved by immunohistochemical positivity for carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin (CK) 5/6, and p63. In this article, we review the clinical and histologic details of 5 patients with SEDC who underwent successful treatment with Mohs micrographic surgery (MMS) at a single institution between November 2018 and May 2020. We also review the histologic patterns that helped distinguish SEDC from SCC upon complete excision. Our findings support the use of MMS as the treatment of choice for SEDC, given that all of the patients we reviewed required more than 1 Mohs stage for complete tumor clearance, and none demonstrated evidence of recurrence or metastasis after a mean follow-up period of 11 months.

A case report of disseminated verrucosis secondary to ustekinumab in a patient with Crohn's disease.

Ustekinumab is a biologic agent with Food and Drug Administration approval for the treatment of moderate-to-severe plaque psoriasis, psoriatic arthritis, ulcerative colitis, and Crohn's disease. It functions to inhibit the p40 subunit common to both interleukin-12 and interleukin-23. These pro-inflammatory cytokines are implicated in autoinflammatory and autoimmune disorders, but they also play an important role in cell-mediated immunity against viral, bacterial, and fungal pathogens. Therefore, antagonism of interleukin-12 and interleukin-23 by ustekinumab may increase the risk of human papillomavirus infection or reactivation which can lead to the development of verrucae. To the best of our knowledge, there is only one published report of disseminated verrucosis secondary to ustekinumab treatment for psoriasis. Here, we present the first case report of ustekinumab-induced disseminated verrucosis occurring in the setting of treatment for Crohn's disease.