Citations

ABSTRACT We report a case of a 71‐year‐old female with acute myeloid leukemia (AML), treated with chemotherapy and hematopoietic stem cell transplant (HSCT), who developed a clonally related non‐Langerhans cell histiocytosis (NLCH). She presented with pink papules on the mid‐upper cutaneous lip and thighs 3 months following HSCT. Skin biopsies revealed a dermal proliferation of cells with eosinophilic cytoplasm. Immunohistochemistry (IHC) studies demonstrated positivity for CD68, CD163, BRAF, cyclin D1, and Factor XIIIa and negativity for CD1a, S100, MPO, and CD20. Next‐generation sequencing (NGS) with a comprehensive myeloid panel revealed corresponding pathogenic mutations to her AML, including BCOR Q176fs*40, IDH1 R132C, and TP53 Y163N, and an additional BRAF V600E mutation. Additional mutations in DNMT3A and KMT2A associated with her AML were not identified. These findings supported the diagnosis of NLCH sharing a clonal origin with the patient's AML. Work up demonstrated isolated cutaneous involvement without AML relapse; therefore, the skin lesions were treated with shave excision, topical tacrolimus 0.1% ointment, and topical clobetasol 0.05% cream without further systemic treatment. The acquired BRAF V600E mutation illustrates the potential for divergent myeloid differentiation and likely explains the emergence of a clonal NLCH after successful AML treatment. Genetic analysis in NLCH can establish clonality with associated hematologic malignancies, uncover actionable mutations, and guide treatment.

ABSTRACT Part I of our three‐part series outlines the essential technical and operational components required for successful digital pathology implementation including hardware, software, and IT infrastructure. It reviews the rationale for digitization, highlighting improvements in workflow efficiency, diagnostic collaboration, and preparedness for computational applications. Key components of Whole Slide Imaging (WSI) systems are discussed, including practical considerations for scanner selection, scanning modalities, and performance trade‐offs relevant to dermatopathology. The article also examines image compression strategies and pyramid image representation, with attention to balancing image quality and storage efficiency. Finally, we review DICOM standards and storage infrastructure options, including cloud, on‐premises, and hybrid models, and associated network bandwidth requirements.

ABSTRACT Background Plasma cell mucositis (PCM) is a rare, chronic inflammatory condition of mucosal surfaces that is likely underdiagnosed and underreported, with limited data on its clinical characteristics, extracavitary involvement, and treatment outcomes. Objectives To characterize the clinical presentation, comorbidities, and treatment patterns of PCM in a cohort of patients from a tertiary care center. Methods We conducted a retrospective cohort study of histopathologically confirmed PCM cases diagnosed at a tertiary care center between 2004 and 2024. Cases were identified based on clinicopathologic correlation demonstrating a polyclonal plasma cell–rich infiltrate. Demographic data, clinical features, comorbidities, laboratory findings, and treatment outcomes were collected and analyzed descriptively. Results Ten patients were included, of whom 7 (70%) were aged ≥ 50 years and 6 (60%) were male. Genital involvement was observed in 6 patients (60%), whereas oral involvement occurred in 4 (40%). Symptom duration exceeded 2 years in 6 patients (60%). Concurrent malignancies were identified in 4 patients (40%), and autoimmune conditions in 2 (20%). Treatment responses were heterogeneous; topical corticosteroids were the most consistently effective therapy, while systemic immunosuppressive agents were required in 3 patients (30%) with variable outcomes. Patch testing identified contact allergens in 2 patients, with improvement following allergen avoidance. Conclusions PCM is a rare and often chronic condition with heterogeneous clinical manifestations and variable therapeutic responses. Genital involvement may be more common than previously recognized. Management remains challenging, highlighting the need for improved understanding of disease pathogenesis and development of more effective treatment strategies.

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory disease with fluctuating activity that requires long-term visual documentation to evaluate disease severity and treatment response. A standardized protocol for photographing HS is critically needed. Objectives: To establish a standardized protocol for using photography to clinically document HS. Methods: We brought together a panel of international experts and used a modified Delphi process to reach consensus on statements about standardized practices for using photography to document HS in clinical practice and research settings. A 75% agreement level was prespecified as the cutoff for consensus. Results: Consensus for photographically documenting HS was developed within 6 key areas: patient preparation, background, lighting, size and reference scale, camera considerations, and patient positioning. The revised and optimized protocol includes 34 standardized reference illustrations. However, the proposed recommendations are for ideal scenarios, and their implementation may not always be practical in a clinical setting. Variations in resources may not have been captured. Conclusions: The proposed consensus-based protocol provides a standard for consistent photographic documentation of HS. This protocol may help clinicians provide better disease surveillance and patient care, and it may aid in more precise and reliable research and clinical trials for HS.

Background: Rheumatoid arthritis is a relatively common rheumatic disease that can present with inflammatory arthritis and subcutaneous nodules. Multicentric reticulohistiocytosis and fibroblastic rheumatism are rarer entities that also present with these features. Methods: Two cases, one of each of fibroblastic rheumatism and multicentric reticulohistiocytosis, are described highlighting characteristic clinical, radiographic, and histologic findings. A narrative review of the literature on these rarer conditions, compared with rheumatoid arthritis, is provided with a focus on articular and cutaneous findings, available information on disease presentations, and key contrasting features that can aid in diagnosis. Results: Radiographic erosion distribution and joint space narrowing, clinical nodule distribution and characteristics, and nodule histology can differ between these diseases. Conclusions: Multicentric reticulohistiocytosis and fibroblastic rheumatism should be considered in the evaluation of seronegative rheumatoid arthritis, especially in cases that do not respond predictably to standard therapies, and cutaneous nodule biopsy can aid in differentiating these three conditions.

Dermatofibrosarcoma protuberans (DFSP) is a rare slow-growing skin cancer with a great capacity for local destruction. DFSP can manifest in a myriad of ways. This case report aims to contribute to the literature by increasing awareness of this condition, along with common diagnostic practices and treatment regimens. We present a 52-year-old Filipino woman who was evaluated for dyspnea with an incidental finding of an indeterminate nodule on imaging. A comprehensive diagnostic workup confirmed dermatofibrosarcoma protuberans (DFSP), which was ultimately treated with surgical resection. Clinically, about 52% of patients are misdiagnosed, leading to poor outcomes. Therefore, awareness, early detection, multidisciplinary treatment, and lifelong screening are essential for optimal outcomes.