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Rigidoporus corticola is a white-rot decay fungus of plants and is widely distributed in North America and Europe (1). R. corticola is a filamentous basidiomycete in the Agaricomycotina subphylum, also [...]

We report 2 cases of infection by fungi unprecedented in Rwanda. One patient with emergomycosis presented with disseminated disease and prominent cutaneous involvement and one patient with African blastomycosis had cutaneous and osseous disease. These cases illustrate the clinicopathologic and molecular traits of novel dimorphic onygenalean species in Rwanda. [ABSTRACT FROM AUTHOR]

Infections remain a major concern following bispecific antibody therapy but are not well described in pivotal trials. We present the first well-documented case of a classic but rare opportunistic infection, disseminated Mycobacterium avium complex, in a patient receiving bispecific antibody therapy. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

Rhinosporidiosis is a tropical disease of the mucous membranes (and, in rare cases, the skin or internal organs) caused by Rhinosporidium seeberi, an enigmatic microorganism of disputed taxonomy (1-3). R. [...]

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 β‐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 β‐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. [ABSTRACT FROM AUTHOR]

A human polyomavirus was recently discovered in Merkel cell carcinoma (MCC) specimens. The Merkel cell polyomavirus (MCPyV) genome undergoes clonal integration into the host cell chromosomes of MCC tumors and expresses small T antigen and truncated large T antigen. Previous studies have consistently reported that MCPyV can be detected in approximately 80% of all MCC tumors. We sought to increase the sensitivity of detection of MCPyV in MCC by developing antibodies capable of detecting large T antigen by immunohistochemistry. In addition, we expanded the repertoire of quantitative PCR primers specific for MCPyV to improve the detection of viral DNA in MCC. Here we report that a novel monoclonal antibody detected MCPyV large T antigen expression in 56 of 58 (97%) unique MCC tumors. PCR analysis specifically detected viral DNA in all 60 unique MCC tumors tested. We also detected inactivating point substitution mutations of TP53 in the two MCC specimens that lacked large T antigen expression and in only 1 of 56 tumors positive for large T antigen. These results indicate that MCPyV is present in MCC tumors more frequently than previously reported and that mutations in TP53 tend to occur in MCC tumors that fail to express MCPyV large T antigen., Introduction Merkel cell carcinoma (MCC) is a rare skin cancer with high risk for metastasis and death (1). MCC has features of a neuroendocrine tumor, with expression of synaptophysin (SYP) [...]