Severe acute myositis and myocarditis on initiation of 6-weekly pembrolizumab post-COVID-19 mRNA vaccination.

We describe three cases of critical acute myositis with myocarditis occurring within 22 days of each other at a single institution, all within 1 month of receiving the initial cycle of the anti-PD-1 drug pembrolizumab. Analysis of T cell receptor repertoires from peripheral blood and tissues revealed a high degree of clonal expansion and public clones between cases, with several T cell clones expanded within the skeletal muscle putatively recognizing viral epitopes. All patients had recently received a COVID-19 mRNA booster vaccine prior to treatment and were positive for SARS-CoV2 Spike antibody.

Five paediatric patients with mycosis fungoides and our approach to provide age-appropriate information and psychological support.

Cutaneous lymphoproliferative diseases in childhood are rare and they are clinically and pathologically heterogeneous, which makes their diagnosis challenging. Although there is limited long-term data and guidance on management, evidence suggests these to be different conditions from cutaneous lymphoma in adults, highlighting the need for age-appropriate patient information. We present clinical outcomes for our paediatric cohort of five patients with mycosis fungoides, emphasizing that despite diagnostic delays, mycosis fungoides in this age group tends to yield a good prognosis.

Patterns of Mucin Deposition in Lichen Planopilaris: A Journey From Follicular "Bubbles" to Perifollicular Fibroplasia.

Lichen Planopiolaris (LPP) is a scarring alopecia characterised by a perifollicular lymphoid cell infiltrate at the level of the infundibulum and isthmus. While perifollicular mucinous fibroplasia is an established finding in LPP, intrafollicular mucin deposition has not been previously reported. We describe two cases with this histopathology and suggest it may represent a helpful clue to the diagnosis of LPP, in the appropriate clinical setting.

Skin-Limited, Methotrexate-Associated Epstein-Barr Virus-Positive Mucocutaneous Ulcer-A Mimicker of High-Grade Lymphoma. A Report of 4 Cases and Review of the Literature.

Immunodeficiency-associated lymphoproliferative disorders (IA-LPDs) constitute a diverse range of conditions including posttransplant lymphoproliferative disorders, other iatrogenic IA-LPDs, and lymphoproliferative disorders associated with an underlying primary immune disorder or HIV infection. IA-LPDs are clinically and pathologically heterogeneous, and there is a lack of standardization of diagnostic terminology. They can represent a potential serious diagnostic pitfall because the histological features of clinically indolent proliferations may mimic those of high-grade lymphoma.

The role of hair follicle counts and ratios in the histopathological assessment of androgenic alopecia, alopecia areata and telogen effluvium: does counting 'count'?

The histopathological assessment of scalp biopsies for the diagnosis of alopecia is most commonly undertaken in specialist centers. Occasionally, pathologists encounter such specimens outside a specialist setting or at a low frequency, which makes a confident diagnosis difficult. A methodical approach is essential to identify and interpret the histopathological findings, and one of the diagnostic tools is the use of follicular counts and ratios.

The Spectrum of Cutaneous Reactive Angiomatoses in End Stage Renal Failure.

Cutaneous reactive angiomatoses encompass a spectrum of conditions driven by underlying occlusive vasculopathy. We present 2 cases of reactive angioproliferation in the context of end-stage renal failure (ESRF) manifesting as painful cutaneous ulceration. The first case demonstrates histologic features of diffuse dermal angiomatosis.

Cutaneous Epstein-Barr virus-associated smooth muscle tumor in immunosuppression.

A 36-year-old renal transplant recipient presented 15 months post-transplantation with a cutaneous spindle cell neoplasm with features of smooth muscle differentiation treated with local excision. 1.4 years later, a magnetic resonance imaging liver scan with gadolinium demonstrated multiple bilobar enhancing hepatic lesions, in keeping with metastases.

Cutaneous intravascular epithelioid hemangioma. A clinicopathological and molecular study of 21 cases.

Pure intravascular growth of epithelioid hemangioma (EH) is exceptional. Herein, we report a series of 21 intravascular EHs, representing a potential serious diagnostic pitfall by mimicking malignant vascular neoplsms with epithelioid morphology. The tumors developed in 12 males and 4 females, aged from 11 to 71 years (mean age 40.

Epstein-Barr Virus-Induced Cutaneous Diffuse Large B-Cell Lymphoma in a Patient With Angioimmunoblastic T-Cell Lymphoma.

Cutaneous manifestations of Epstein-Barr virus (EBV)-driven B-cell lymphoid proliferations occur rarely as a result of severe immunodeficiency. To date, only a few cases of extranodal EBV-associated B-cell lymphomas arising in patients with angioimmunoblastic T-cell lymphoma (AITL) have been reported, and less common is a cutaneous presentation. AITL is a rare aggressive tumor that carries a poor prognosis and prompt diagnosis, and recognition of EBV-associated diffuse B-cell lymphoma is essential in these patients to instigate the correct treatment.

Expanding the clinical spectrum of dermal hyperneury: report of nine new cases and a review of the literature.

Aims: Dermal hyperneury is defined as the hypertrophy of small nerves in the dermis. It has been described in a variety of settings. We present a series of nine new cases with a distinctive clinical presentation and review the existing literature.

Cutaneous hyperpigmentation and familial gastrointestinal stromal tumour associated with KIT mutation.

Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours arising in the gastrointestinal tract. Early detection, before metastasis occurs, is important as complete surgical excision achieves cure. Approximately 85% of GISTs are associated with mutations in the KIT gene, and although the majority of GISTs are sporadic, familial GISTs have been identified.

Poroid hidradenoma in the hand: A case report and systematic review.

Poroid hidradenoma (PH) is a rare benign neoplasm of the skin appendages. There are currently no guidelines for its management, and little information available regarding the natural history, treatment options, or outcomes. Systematic literature review identified 19 cases of isolated PH.

Myxoinflammatory fibroblastic sarcoma: morphologic and genetic updates.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a malignant mesenchymal neoplasm most frequently arising in the distal extremities of adults, which usually behaves in a low-grade manner but is capable of metastasizing to local and distant sites, rarely leading to death. It is a rare tumor whose unusual morphology can lead to erroneous histologic diagnosis, either as a nonneoplastic (infectious or inflammatory) process or as a variety of neoplastic diseases. While its exact origin is uncertain, ultrastructural studies have shown at least some of the constituent cells to be modified fibroblasts.

Cutaneous PEComa: a rare entity to consider in an unusual site.

PEComa is a mesenchymal neoplasm thought to derive from the perivascular epithelioid cell, a hypothetical cell type not yet identified. PEComa is a broad term that was recently expanded to include visceral, retroperitoneal, and somatic soft tissue, in addition to cutaneous tumors, which share morphological and immunohistochemical features in common with angiomyolipoma, lymphangiomyomatosis, and clear cell "sugar" tumor. The latter have distinct, site-related, clinical, morphological, and biological features.

Heterologous osteosarcomatous and rhabdomyosarcomatous elements in dedifferentiated solitary fibrous tumor: further support for the concept of dedifferentiation in solitary fibrous tumor.

Dedifferentiation within solitary fibrous tumor is a rare and only recently characterized phenomenon. It differs from malignant solitary fibrous tumor in that there is abrupt transition between classical solitary fibrous tumor and the dedifferentiated component. The latter is a high-grade sarcoma, which can exhibit a number of morphologies, but heterologous differentiation is exceptionally rare.