Generalized pustular psoriasis-like widespread eruption following COVID-19 infection in a patient with spondyloarthropathy on adalimumab.

Generalized pustular psoriasis (GPP) is a form of pustular psoriasis that is distinguished by recurring or persistent outbreaks of non-acral primary sterile pustules. These eruptions can occur with or without systemic inflammation. Various factors, such as medications, stress and viral infection, have been identified as potential triggers for GPP flares. While several cases have detailed GPP-like eruptions in the setting of coronavirus disease 2019 (COVID-19) infection, few have explored the interplay between infection and biologic use in the development of GPP. In this case, we detail the history and management of a 45-year-old male patient with a prior history of spondyloarthropathy managed on a tumour necrosis factor-α inhibitor and recent COVID-19 infection presenting with a new, spreading pustular rash.

Erythrasma of the Vulva: An Invisible Dermatosis.

Erythrasma is a prevalent superficial bacterial infection typically caused by Corynebacteria species and preferentially affecting intertriginous sites including axillary, interdigital, and inguinal skin folds. However, erythrasma of the vulva is uncommon, with only 2 cases previously reported. Although erythrasma can be diagnosed clinically using Woods lamp examination, it may not always be considered in the differential diagnosis for patients presenting with persistent vulvar pruritus. We report 12 cases of vulvar erythrasma identified by histopathology, with a review of clinical and histologic features. The mean patient age was 60.1 yr and the mean patient BMI was 30.5. Five of 12 patients presented with pruritic rash. The time from symptom onset to diagnosis was 9 mo in 1 case, >18 mo in 4 cases, and unknown in the remaining cases. The characteristic histologic features were compact orthokeratosis and mild perivascular chronic inflammation. In all 12 cases, Periodic Acid-Schiff-diastase (PAS-D) staining highlighted intracorneal filamentous rods which were not readily appreciable on H&E. After the diagnosis of erythrasma, 4 patients were treated with topical lincomycin, of whom 3 had clinical improvement in symptoms. One patient was treated with topical macrolide antibiotic and also reported improvement in symptoms. Consideration of erythrasma on the differential for patients presenting with vulvar rash and pruritus may shorten the time to diagnosis and treatment, minimize patient discomfort, and reduce the scope and cost of diagnostic testing.

Stress from Nucleotide Depletion Activates the Transcriptional Regulator HEXIM1 to Suppress Melanoma.

Studying cancer metabolism gives insight into tumorigenic survival mechanisms and susceptibilities. In melanoma, we identify HEXIM1, a transcription elongation regulator, as a melanoma tumor suppressor that responds to nucleotide stress. HEXIM1 expression is low in melanoma. Its overexpression in a zebrafish melanoma model suppresses cancer formation, while its inactivation accelerates tumor onset in vivo. Knockdown of HEXIM1 rescues zebrafish neural crest defects and human melanoma proliferation defects that arise from nucleotide depletion. Under nucleotide stress, HEXIM1 is induced to form an inhibitory complex with P-TEFb, the kinase that initiates transcription elongation, to inhibit elongation at tumorigenic genes. The resulting alteration in gene expression also causes anti-tumorigenic RNAs to bind to and be stabilized by HEXIM1. HEXIM1 plays an important role in inhibiting cancer cell-specific gene transcription while also facilitating anti-cancer gene expression. Our study reveals an important role for HEXIM1 in coupling nucleotide metabolism with transcriptional regulation in melanoma.

Teaching Infectious Disease Pathology and Taking it To Africa.

With the advent of increasing emerging infectious diseases, rising antibiotic resistance, and the growing number of immunocompromised patients, there is increasing demand for infectious disease (ID) pathology expertise and microbiology testing. Currently, ID pathology training and emerging molecular microbiology techniques (eg, metagenomic next-generation sequencing and whole genome sequencing) are not included in the most American Council of Graduate Medical Education medical microbiology fellowship curricula, and not surprisingly, many institutions lack anatomical pathologists with expertise in ID pathology and advanced molecular diagnostics. In this article, we describe the curriculum and structure of the Franz von Lichtenberg Fellowship in Infectious Disease and Molecular Microbiology at Brigham and Women's Hospital in Boston, MA. We emphasize the value of a training model that strives to integrate anatomical pathology, clinical pathology, and molecular pathology by providing examples in a case-based format and presenting selected metrics of the potential effect of such integrative ID pathology service and briefly describing opportunities and challenges of our global health efforts in Rwanda.

Deep-penetrating-nevus-like melanoma arising in patients with familial adenomatous polyposis syndrome.

Deep penetrating nevi (DPN) are uncommon but distinctive melanocytic neoplasms that show an epithelioid to spindle cell morphology, prominent pigmentation with melanophages, and a plexiform growth pattern. Molecularly, most DPN are thought to be characterized by dual activation of the mitogen-activated protein kinase and the wingless-related integration site (Wnt) pathways, the latter being most commonly driven by activating ß-catenin mutations. DPN-like melanomas are very rare but can be recognized through their overlapping morphologic and architectural features with DPN. Familial adenomatous polyposis (FAP) is a hereditary cancer predisposition syndrome associated with multiple tumor types including colorectal carcinoma and desmoid fibromatosis. Like DPN, FAP is also driven by activation of the Wnt pathway, most commonly through loss of function mutations in APC, which is a major negative regulator of ß-catenin. Here we report two cases of DPN-like melanoma arising in FAP patients. While the small number of cases precludes definitive establishment of an etiologic link between these entities, the shared molecular pathogenesis of DPN-like lesions and FAP suggests that FAP patients may be at increased risk for this rare subtype of melanoma.

A Novel Fusion Partner, SP100, Drives Nuclear Dot Localization of ALK in Epithelioid Fibrous Histiocytoma.

ABSTRACT: Epithelioid fibrous histiocytoma (EFH) is a distinctive benign cutaneous neoplasm composed of uniform epithelioid cells, often with binucleated cells. EFH are characterized by the presence of anaplastic lymphoma kinase ( ALK ) gene rearrangements with a variety of binding partners. These rearrangements result in the overexpression of ALK , which can be detected using immunohistochemistry. Cytoplasmic ALK expression is by far the most common pattern encountered. Here, we describe a case of EFH with a distinctive intranuclear dot-like ALK expression pattern. Subsequent next-generation DNA sequencing revealed a novel SP100::ALK gene fusion. Speckled protein-100 (SP100) is a constituent of nuclear dots, also known as promyelocytic leukemia bodies, which are still poorly understood membraneless subnuclear structures. Thus, this novel ALK fusion partner seems to explain this distinctive pattern of ALK localization. We examined ALK expression patterns in 11 other cases of EFH, but all showed typical cytoplasmic localization. This study expands the morphologic and molecular spectrum of EFH, provides a dramatic illustration of the ability of fusion partners to control protein localization, and implies that tumorigenic ALK signaling may occur at a variety of subcellular locations.

Rigidoporus corticola Colonization and Invasive Fungal Disease in Immunocompromised Patients, United States.

We report 2 cases of Rigidoporus corticola (Oxyporus corticola) infection in humans in the United States. Clinical manifestations consisted of angioinvasive fungal sinusitis in 1 patient and pulmonary intracavitary fungus ball in the other patient. These cases illustrate previously undescribed clinicopathologic manifestations of infection by this filamentous basidiomycete in humans.

Proficiency at Tick Identification by Pathologists and Clinicians Is Poor.

OBJECTIVES: Prompt accurate identification of tick species is required for appropriate administration of single dose antimicrobial prophylaxis for Lyme disease in selected patients. To determine the proficiency of clinicians at tick identification in the northeastern United States where Lyme disease has its highest incidence, we undertook a survey. METHODS: We analyzed the results of a voluntary survey testing proficiency in identifying tick species using high-resolution photographs of ticks. RESULTS: Only 35% of ticks were correctly identified. Although 60% of respondents could identify a nonengorged adult blacklegged tick, only 34% could correctly identify a partially engorged blacklegged tick. Participants performed even worse at classifying brown dog, American dog, and Lone Star ticks. CONCLUSIONS: Proficiency of tick identification by pathologists and clinicians is poor.

Identification of Hard Ticks in the United States: A Practical Guide for Clinicians and Pathologists.

ABSTRACT: According to guidelines published by the Infectious Disease Society of America, Lyme disease prophylaxis is possible if a tick can be identified as Ixodes scapularis (nymphal or adult) within 72 hours of tick removal. However, a recent survey of medical practitioners indicates generally poor proficiency in tick identification. In this study, we provide a simple, practical guide to aid medical practitioners in identifying the most commonly encountered human biting ticks of North America.

Morphologic, Immunohistochemical, and Molecular Distinction Between Fibroepithelioma of Pinkus and "Fenestrated" Basal Cell Carcinoma.

Fibroepithelioma of Pinkus (FEP) is a rare cutaneous neoplasm with a characteristic fenestrated architecture and a prominent spindle cell stromal component and which invariably pursues an indolent course. The classification of FEP has been much debated since its first description in 1953, with some arguing that it represents a variant of a basal cell carcinoma (BCC) while others view it as a variant of a trichoblastoma. Multiple previous immunohistochemical studies aiming to clarify this issue have yielded conflicting results. To date, there have been no molecular studies of FEP. We identified 16 cases of fenestrated follicular neoplasms and classified them as BCC or FEP based solely on histomorphologic criteria. CK20 immunohistochemistry supported this classification scheme, with FEP showing significantly more CK20-positive Merkel cells than BCC. We then analyzed a subset of these tumors by a targeted next-generation DNA sequencing platform. All the BCC cases harbored pathogenic PTCH1 mutations, confirming the diagnosis. By contrast, none of the FEP cases harbored a PTCH1 mutation or indeed any mutation known to be causally linked to the development of BCC. Our results suggest that FEP can be distinguished from BCC on morphologic, immunohistochemical, and molecular genetic grounds. We argue that FEP is better considered a benign follicular neoplasm and support its classification as a variant of trichoblastoma.

Cluster of Nasal Rhinosporidiosis, Eastern Province, Rwanda.

We report 4 recent cases of nasal rhinosporidiosis in Rwanda. All patients were boys or young men living in the same district (Gatsibo District, Eastern Province), suggesting a reservoir in the area. The recent reemergence of rhinosporidiosis in Rwanda might reflect increased availability of diagnostic services rather than emerging disease.

Frozen sections are unreliable for the diagnosis of necrotizing soft tissue infections.

Necrotizing soft tissue infections are rare but are associated with high rates of morbidity and mortality. The use of bedside or intraoperative frozen sections has been reported to be associated with faster diagnosis and better outcomes; however, to date no large studies have been published to determine the sensitivity and specificity of frozen sections in this setting. Twenty years of cases suspicious for necrotizing soft tissue infection at a large academic referral center were reviewed, blinded to the final clinical diagnosis (gold standard). Cases were assessed for the number of neutrophils, extent of necrosis, presence of thrombi, bacteria, karyorrhexis, and fibrin, and concordance with permanent sections. A total of 166 cases suspicious for necrotizing soft tissue infection had frozen section slides available for review. Sixty-three cases were clinically determined to be positive and 103 negative. Neutrophils, necrosis, thrombi, bacteria, karyorrhexis, and fibrin were present in both positive and negative cases; however, no histological feature or combination of features was found to be both sensitive and specific for necrotizing soft tissue infection. The combined presence of necrosis and frequent neutrophils was 73% sensitive and 68% specific, with a 58% positive predictive value and 80% negative predictive value. The additional observation of bacteria decreased sensitivity to 32%, whereas raising specificity to 91%, with 69% positive predictive value and 68% negative predictive value. Thirty-two cases (19%) contained findings identified on permanent sections (eg, bacteria) not observed on frozen section slides, highlighting the risk of false negatives owing to technical limitations or sampling errors. Frozen sections in necrotizing soft tissue infections and negative cases may show similar histological findings. Combined with the risk of false negatives, these results suggest that frozen sections are likely to be of limited clinical utility due to lack of sensitivity and specificity, and risk for delayed diagnosis and treatment.

Epidermodysplasia Verruciformis-like HPV Infection of the Vulva in Immunosuppressed Women.

The vast majority of vulvar human papilloma virus infections are produced by α human papilloma viruses and consist of exophytic or flat warts and classic or "usual" vulvar intraepithelial neoplasia. This report details 2 examples of epidermodysplasia verruciformis-like lesions of the vulva in women who were immunosuppressed. The most consistent morphologic feature was the presence of abnormal mature keratinocytes with large pale open nuclei with small nucleoli and eosinophilic cytoplasm, situated in the upper epithelial layers. In addition to these features, which are commonly seen in epidermodysplasia verruciformis-associated lesions, 1 case displayed in addition more extensively distributed abnormal nuclei, including involvement of both the upper epithelial strata and the epithelial/stromal interface. Both lesions were associated with ß-papilloma virus type 5. The unique aspects of epidermodysplasia verruciformis-like lesions relative to the more common human papilloma virus infections of the vulva are highlighted and these cases illustrate the range of epithelial distribution that might be encountered in lesions involving the vulvar mucosa.

Atypical hand, foot and mouth disease in adults associated with coxsackievirus A6: a clinico-pathologic study.

BACKGROUND: Hand, foot, and mouth disease (HFMD) is a contagious illness most commonly occurring in children 5 years old or younger. The most common cause of HFMD in the United States is Coxsackievirus A16. HFMD is uncommon in adults, and may show other atypical features including a broader spectrum of cutaneous involvement and a greater degree of severity. METHODS: We evaluated the clinical, histopathologic and molecular features of three cases of atypical HFMD occurring in adults. RESULTS: All three cases showed clinical features that were worrisome for erythema multiforme or a disseminated herpesvirus infection. The histopathologic findings were quite uniform, and showed intraepidermal vesiculation with a predominantly neutrophil-rich infiltrate. A characteristic feature was the specific involvement of the upper stratum spinosum and stratum granulosum, with relative sparing of the stratum corneum. In none of the cases was there evidence of herpesvirus. Molecular analysis performed on two of the cases showed involvement by Coxsackievirus A6, an uncommon serotype in HFMD. All three cases resolved spontaneously. CONCLUSIONS: Atypical HFMD associated with Coxsackievirus A6 represents an uncommon and potentially diagnostically challenging cutaneous eruption. Its recognition is critical to avoid unneeded therapy and to establish accurate prognostic expectations.

5-Hydroxymethylcytosine expression in metastatic melanoma versus nodal nevus in sentinel lymph node biopsies.

Sentinel lymph node biopsies are conducted to stage patients with newly diagnosed melanomas that have histopathological attributes conferring defined levels of metastatic potential. Because benign nevic cells may also form 'deposits' in lymph nodes (nodal nevus), the pathological evaluation for metastatic melanoma within sentinel lymph nodes can be challenging. Twenty-eight sentinel lymph node biopsy cases containing either metastatic melanoma (N=18) or nodal nevi (N=10) were retrieved from the archives of the Brigham and Women's Hospital, Department of Pathology (2011-2014). In addition, two sentinel lymph node cases that were favored to represent metastatic disease but whose histopathological features were viewed as equivocal, with melanoma favored, were also included. Dual labeling for the melanocyte lineage marker, MART-1, and the epigenetic marker, 5-hydroxymethylcytosine, a functionally significant indicator that has been shown to distinguish benign nevi from melanoma, was performed on all cases using immunohistochemistry and/or direct immunofluorescence. All (18 of 18) metastatic melanoma cases showed complete loss of 5-hydroxymethylcytosine nuclear staining in MART-1-positive cells, and all (10 of 10) nodal nevus cases demonstrated 5-hydroxymethylcytosine nuclear staining in MART-1-positive cells. In addition, 5-hydroxymethylcytosine staining confirmed the favored diagnoses of metastatic melanoma in the two 'equivocal' cases. Thus, 5-hydroxymethylcytosine may be a useful adjunctive marker to distinguish between benign nodal nevi and metastatic melanoma during the evaluation of sentinel lymph node biopsies for metastatic melanoma.

Impact of the 2009 AJCC staging guidelines for melanoma on the number of mitotic figures reported by dermatopathologists at one institution.

BACKGROUND: In 2009 the revised seventh staging system for melanoma recommended the use of mitotic count to separate stage T1a from T1b. However, careful scrutiny of cases may lead to an inadvertent selection effect, with consequent increased reporting of mitotic counts. METHODS: We investigated whether there is a significant increase in mitotic counts reported since 2009 for melanomas with a Breslow thickness of 1.0 mm or less. We conducted a retrospective, case-controlled study examining invasive melanoma cases at a large academic center. Mitotic counts were compared between pathology reports before 2009 (n = 61) and after 2009 (n = 125), with a subset of slides re-examined in a blinded fashion. RESULTS: Before the 2009 staging guidelines, 51% of cases had one or more mitosis reported compared to 38% after 2009 (p = 0.113). Blinded re-counting did not yield a significant difference when compared with the original pathology reports in either group. CONCLUSIONS: There was not a significant difference in the number of mitoses reported after the implementation of the new guidelines.

Malignant Eccrine Spiradenoma of the Face.

Malignant eccrine spiradenoma, or spiradenocarcinoma, is an exceedingly rare sweat-gland tumor, with only 102 reported cases. Low-grade carcinomas are especially rare with only a few cases reported. Because of the limited number of case reports, the biologic behavior of low-grade malignant eccrine spiradenoma is poorly understood and no evidence-based therapeutic approach is established. Here, the authors report a 29-year-old woman who presented with a history of left-sided facial lesions present since the age of 2 months. Histopathologic examination revealed multiple benign spiradenomas, several of which showed foci of low-grade malignant transformation evidenced by loss of the characteristic 2-cell population seen in the benign tumor component. Included are the clinical presentation, histopathologic description, and surgical decision making in an effort to guide recognition of this rare entity.

Biomarker evaluation of face transplant rejection: association of donor T cells with target cell injury.

This series of 113 sequential biopsies of full facial transplants provides findings of potential translational significance as well as biological insights that could prompt reexamination of conventional paradigms of effector pathways in skin allograft rejection. Serial biopsies before, during, and after rejection episodes were evaluated for clinicopathological assessment that in selected cases included specific biomarkers for donor-versus-recipient T cells. Histologic evidence of rejection included lymphocyte-associated injury to epidermal rete ridges, follicular infundibula, and dermal microvessels. Surprisingly, during active rejection, immune cells spatially associated with target cell injury consisted abundantly or predominantly of lymphocytes of donor origin with an immunophenotype typical of the resident memory T-cell subset. Current dogma assumes that skin allograft rejection is mediated by recipient T cells that attack epidermal targets, and the association of donor T cells with sites of target cell injury raises questions regarding the potential complexity of immune cell interactions in the rejection process. A more histopathologically refined and immune-based biomarker approach to assessment of rejection of facial transplants is now indicated.