Cutaneous larva migrans in the northeastern US.

Cutaneous larva migrans (CLM) is a dermo-epidermal parasitic infection with a disproportionate incidence in developing countries, particularly in, and near tropical areas. It is characterized by erythematous, twisting, and linear plaques that can migrate to adjacent skin. Herein, we present an otherwise healthy 45-year-old woman who acquired a pruritic, erythematous, and serpiginous rash localized to her right medial ankle during a trip to New England. Oral ivermectin, the preferred first-line treatment for cutaneous larva migrans, was administered in combination with triamcinolone. This was followed by removal of the papular area via punch biopsy; treatment was successful with a one-week recovery. Although cutaneous larva migrans has traditionally been considered a tropical disease, clinicians should be cognizant of its expanding geographic spread.

Incidence Trends of Primary Cutaneous T-Cell Lymphoma in the US From 2000 to 2018: A SEER Population Data Analysis.

Using SEER database data, this cohort study analyzed cutaneous T-cell lymphoma incidence by tumor subtype, sex, age, race and ethnicity, socioeconomic status, and geography.

Disparities in dermatology AI performance on a diverse, curated clinical image set.

An estimated 3 billion people lack access to dermatological care globally. Artificial intelligence (AI) may aid in triaging skin diseases and identifying malignancies. However, most AI models have not been assessed on images of diverse skin tones or uncommon diseases. Thus, we created the Diverse Dermatology Images (DDI) dataset-the first publicly available, expertly curated, and pathologically confirmed image dataset with diverse skin tones. We show that state-of-the-art dermatology AI models exhibit substantial limitations on the DDI dataset, particularly on dark skin tones and uncommon diseases. We find that dermatologists, who often label AI datasets, also perform worse on images of dark skin tones and uncommon diseases. Fine-tuning AI models on the DDI images closes the performance gap between light and dark skin tones. These findings identify important weaknesses and biases in dermatology AI that should be addressed for reliable application to diverse patients and diseases.

Spitz nevus with EHBP1-ALK fusion and distinctive membranous localization of ALK.

ALK rearrangements define a histopathologically distinctive yet diverse subset of Spitz tumors characterized by fusiform to epithelioid melanocytes with frequent fascicular growth and ALK overexpression. Molecularly, these tumors are characterized by fusions between ALK and a variety of gene partners, most commonly TPM3 and DCTN1. We describe an unusual case of a Spitz nevus occurring in a 13-year-old female that manifested ALK immunopositivity with cell membrane localization. The proliferation was polypoid and composed of elongated nests of epithelioid melanocytes with enlarged nuclei, prominent nucleoli, and abundant cytoplasm without significant atypia and lacking mitotic figures. The nevus exhibited strong and diffuse expression of p16. Targeted next-generation RNA sequencing revealed an in-frame EHBP1-ALK fusion, which has been reported only once in the literature. EHBP1 encodes an adaptor protein with plasma membrane targeting potential. Together, these findings suggest that the 5' ALK fusion partner in Spitz tumors may dictate the subcellular localization of the ALK chimeric oncoprotein. In summary, this case highlights a rare ALK fusion associated with a distinct immunohistochemical staining pattern and further expands the spectrum of ALK-rearranged melanocytic tumors.

Artificial intelligence for dermatopathology: Current trends and the road ahead.

Artificial intelligence (AI), including deep learning methods that leverage neural network-based algorithms, hold significant promise for dermatopathology and other areas of diagnostic pathology in research and clinical practice. There has been significant progress over past several years in applying AI to analyzing digital histopathology images for diagnosis. While much work in AI analysis of histopathology data remains investigational, recent regulatory agency approval in Europe and United States of AI-assisted tools for clinical use in histopathologic diagnosis of prostate and breast cancer herald broader movement of AI into the clinical diagnostic realm of anatomic pathology, including dermatopathology. However, significant challenges remain in translating AI from research into clinical practice, including algorithmic real-world performance, robustness to variation in data sets and practice settings, effective integration into clinical workflows, and cost effectiveness. This review introduces core concepts and terminology in AI, and assesses current progress and challenges in applying AI to dermatopathology.

Next-generation sequencing confirms T-cell clonality in a subset of pediatric pityriasis lichenoides.

BACKGROUND: Pityriasis lichenoides (PL) is a papulosquamous disease that affects both adults and children. Previous studies have shown a subset of this entity to have clonal T-cell populations via PCR-based assays. In this study, we sought to implement next-generation sequencing (NGS) as a more sensitive and specific test to examine for T-cell clonality within the pediatric population. METHODS: We identified 18 biopsy specimens from 12 pediatric patients with clinical and histopathologic findings compatible with PL. Patient demographics, clinical features, management, and histopathologic findings were reviewed. All specimens were analyzed for clonality with NGS of T-cell receptor beta (TRB) and gamma (TRG) genes. RESULTS: Of the 12 patients, 9 (75%) had complete resolution of lesions at the time of data collection (mean follow-up 31 months). The remaining three patients significantly improved with methotrexate (with or without acitretin). Interestingly, 7 of 12 patients (58%) and 9 of 17 biopsy specimens (53%) showed evidence of T-cell clonality. Two patients showed matching TRB clones from different anatomic sites. CONCLUSIONS: T-cell clonality is a common finding in PL, probably representing a "reactive clonality" rather than a true lymphoproliferative disorder. Clonality alone cannot be used as a means to distinguish PL from lymphomatoid papulosis or cutaneous lymphoma.

Appropriate use criteria for ancillary diagnostic testing in dermatopathology: New recommendations for 11 tests and 220 clinical scenarios from the American Society of Dermatopathology Appropriate Use Criteria Committee.

BACKGROUND: Appropriate use criteria (AUC) provide patient-centered physician guidance in test selection. An initial set of AUC was reported by the American Society of Dermatopathology (ASDP) in 2018. AUC reflect evidence collected at single timepoints and may be affected by evolving evidence and experience. The objective of this study was to update and expand AUC for selected tests. METHODS: RAND/UCLA (RAND Corporation [Santa Monica, CA]/University of California Los Angeles) methodology used includes the following: (a) literature review; (b) review of previously rated tests and previously employed clinical scenarios; (c) selection of previously rated tests for new ratings; (d) development of new clinical scenarios; (e) selection of additional tests; (f) three rating rounds with feedback and group discussion after rounds 1 and 2. RESULTS: For 220 clinical scenarios comprising lymphoproliferative (light chain clonality), melanocytic (comparative genomic hybridization, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, telomerase reverse transcriptase promoter), vascular disorders (MYC), and inflammatory dermatoses (periodic acid-Schiff, Gömöri methenamine silver), consensus by panel raters was reached in 172 of 220 (78%) scenarios, with 103 of 148 (70%) rated "usually appropriate" or "rarely appropriate" and 45 of 148 (30%), "appropriateness uncertain." LIMITATIONS: The study design only measures appropriateness. Cost, availability, test comparison, and additional clinical considerations are not measured. The possibility that the findings of this study may be influenced by the inherent biases of the dermatopathologists involved in the study cannot be excluded. CONCLUSIONS: AUC are reported for selected diagnostic tests in clinical scenarios that occur in dermatopathology practice. Adhering to AUC may reduce inappropriate test utilization and improve healthcare delivery.

Immunohistochemical ALK Expression in Granular Cell Atypical Fibroxanthoma: A Diagnostic Pitfall for ALK-Rearranged Non-neural Granular Cell Tumor.

ABSTRACT: Atypical fibroxanthoma (AFX) is a neoplasm that most commonly occurs on sun-damaged skin of the head and neck in elderly patients and that usually exhibits indolent clinical behavior with complete excision. The granular cell variant of AFX demonstrates overlapping histopathologic features with dermal non-neural granular cell tumor (NNGCT), which typically arises on the extremities of young to middle aged adults with rare reports of regional metastasis. A subset of NNGCT harbors ALK rearrangements and expresses ALK by immunohistochemistry. Here, we present 2 cases of granular cell AFX occurring on the scalp of males aged 73 and 87 with ALK expression by immunohistochemistry and no evidence of an ALK rearrangement on fluorescence in situ hybridization, representing a diagnostic pitfall for NNGCT.

TrueImage: A Machine Learning Algorithm to Improve the Quality of Telehealth Photos.

Telehealth is an increasingly critical component of the health care ecosystem, especially due to the COVID-19 pandemic. Rapid adoption of telehealth has exposed limitations in the existing infrastructure. In this paper, we study and highlight photo quality as a major challenge in the telehealth workflow. We focus on teledermatology, where photo quality is particularly important; the framework proposed here can be generalized to other health domains. For telemedicine, dermatologists request that patients submit images of their lesions for assessment. However, these images are often of insufficient quality to make a clinical diagnosis since patients do not have experience taking clinical photos. A clinician has to manually triage poor quality images and request new images to be submitted, leading to wasted time for both the clinician and the patient. We propose an automated image assessment machine learning pipeline, TrueImage, to detect poor quality dermatology photos and to guide patients in taking better photos. Our experiments indicate that TrueImage can reject ~50% of the sub-par quality images, while retaining ~80% of good quality images patients send in, despite heterogeneity and limitations in the training data. These promising results suggest that our solution is feasible and can improve the quality of teledermatology care.

ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism.

Historically recognized by their characteristic histopathologic features, Spitz neoplasms are now known to be molecularly defined by mutually exclusive recurrent abnormalities that cause activation of the MAPK pathway. Spitz neoplasms with ALK rearrangements frequently demonstrate polypoid growth with a plexiform arrangement of nested, fusiform melanocytes in intersecting fascicles. Although neurotropism has been described in indolent Spitz neoplasms, this feature is not frequently mentioned in publications on histopathologic assessment of this group of melanocytic tumors. Here, we present an unusual case of a 3-year-old female with an ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism occurring on the vermilion border of the lower lip.

Concurrent Trypanosoma cruzi and Cytomegalovirus Reactivation in an Immunosuppressed Patient With Limited Cutaneous Systemic Sclerosis.

Chagas disease, a multisystem infection caused by the protozoan Trypanosoma cruzi, is primarily found in Latin America. In recent years, prevalence has increased in the United States, where reactivation is the most common clinical scenario. Here, we describe cutaneous reactivation of T. cruzi in a patient with limited cutaneous systemic sclerosis on immunosuppression therapy who simultaneously presented with cytomegalovirus reactivation. Histopathology showed parasitized histiocytes in the superficial and deep dermis. Occasional epidermal keratinocytes were also parasitized, and rare organisms were also seen in the walls of blood vessels. Also noted were viral cytopathic changes within the vascular endothelium, and immunostaining confirmed cytomegalovirus. In this report, we describe the difference in cutaneous findings between reactivated and acute Chagas disease, and we also review the histopathologic features that help distinguish T.cruzi from other intracellular organisms.

Cutaneous T-cell lymphomas with pathogenic somatic mutations and absence of detectable clonal T-cell receptor gene rearrangement: two case reports.

BACKGROUND: Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of extranodal non-Hodgkin lymphomas for which diagnosis can be challenging given the potential for overlap with inflammatory dermatoses. Current diagnostic criteria for CTCL incorporate clinical and histopathologic findings as well as results of T-cell receptor (TCR) gene sequencing. Molecular interrogation of TCR genes, TRG and TRB, has proven to be a critical tool for confirming diagnoses of CTCL and for disease tracking after initiation of therapy or after stem cell transplant. Methods for confirming a diagnosis of lymphoma in the absence of TCR gene clonality are lacking. We present two patients with CTCL with pathogenic somatic mutations in the absence of TRG and TRB clonality. CASE PRESENTATIONS: Case 1: A 38-year-old male had a 19-year history of a diffuse skin rash with papulosquamous, granulomatous, and verrucous features and progressive ulcerated plaques and tumors demonstrating an atypical CD4+ T-cell infiltrate with expression of cytotoxic markers CD56, TIA-1, granzyme, and perforin on histopathology. No definitive evidence for T-cell clonality was detected by conventional PCR of 6 biopsies or by next-generation sequencing (NGS) of 14 biopsies. Somatic mutational profiling of a skin biopsy revealed pathogenic mutations in PIKC3D and TERT promoter hotspots, confirming the presence of a clonal process. Case 2: A 69-year-old male with a 13-year history of progressive, diffuse hypertrophic and eroded plaques showed an atypical CD4+ T-cell infiltrate with subset expression of TIA-1 and granzyme on histopathology. No TCR clonality was detected by TCR-NGS of 6 biopsies. Somatic mutational profiling of a skin biopsy detected a pathogenic mutation in TP53, confirming the presence of a clonal process. CONCLUSIONS: These cases highlight how detection of pathogenic somatic mutations can confirm a diagnosis of lymphoma in a clinically and histopathologically suspicious cutaneous lymphoid proliferation without detectable TCR clonality.

Histopathologic Characterization of Mogamulizumab-associated Rash.

Rash is one of the most common adverse events observed with mogamulizumab, an anti-C-C chemokine receptor 4 monoclonal antibody approved for previously treated mycosis fungoides (MF) and Sezary syndrome (SS). Given the nonspecific clinical presentations of this rash, histopathologic distinction from MF/SS is critical for informing clinical management. We performed a comprehensive characterization of the histopathologic findings in mogamulizumab-associated rash (MAR) with the integration of high-throughput sequencing of T-cell receptor (TCR) genes. Fifty-two biopsy specimens from 19 patients were evaluated retrospectively. Three major histologic reaction patterns were identified: spongiotic/psoriasiform dermatitis (33/52), interface dermatitis (11/52), and granulomatous dermatitis (8/52). Almost half of the specimens (21/52) showed at least 2 of these reaction patterns concurrently. Dermal eosinophils were not a consistent feature, being present in only half (27/52) of specimens and prominent in only 3. Features mimicking MF/SS, including lymphocyte exocytosis, lamellar fibroplasia, and adnexal involvement, were commonly seen but tended to be focal and mild. In 38/43 specimens with available immunohistochemistry, intraepidermal lymphocytes demonstrated a CD4:CD8 ratio ≤1 : 1. Low background levels of the patient's previously identified MF/SS-associated TCR sequence(s) were demonstrated in 20/46 specimens analyzed by high-throughput sequencing of TCR. We conclude that MAR may demonstrate diverse histologic features. Findings that may distinguish MAR from MF/SS include the inverted or normalized CD4:CD8 ratio within intraepidermal lymphocytes and demonstration of absent or nondominant levels of disease-associated TCR sequences. Correlation with the clinical findings and immunohistochemical and molecular characterization of the patient's MF/SS before mogamulizumab, when possible, may facilitate recognition of MAR.

PRAME expression in melanocytic proliferations with intermediate histopathologic or spitzoid features.

BACKGROUND: PRAME (PReferentially expressed Antigen in MElanoma) has shown utility in distinguishing melanoma from benign melanocytic lesions, but knowledge of its expression pattern in intermediate melanocytic and spitzoid proliferations is limited. METHODS: Immunohistochemical expression of PRAME was examined in 112 melanocytic proliferations with intermediate histopathologic or spitzoid features. RESULTS: Any intensity of nuclear PRAME staining in at least 60% of lesional melanocytes was determined as the best threshold for diffuse staining in this cohort. Nearly all non-spitzoid melanomas (23/24; 95.8%) demonstrated diffuse PRAME expression. PRAME was completely negative in 95.6% (43/45) of mitotically-active nevi, traumatized nevi, nevi with persistent/recurrent features, and dysplastic nevi. Most Spitz nevi (15/20) and atypical Spitz tumors (10/13) entirely lacked PRAME expression. One Spitz nevus, one atypical Spitz tumor, and one spitzoid melanoma (1/2) demonstrated diffuse PRAME expression. CONCLUSIONS: Although diffuse PRAME expression is generally limited to malignant melanoma, benign Spitz nevi and atypical Spitz tumors can infrequently express diffuse PRAME. PRAME immunohistochemistry can be useful in the evaluation of atypical melanocytic proliferations with intermediate histopathologic features but should be interpreted with caution in the setting of spitzoid neoplasms.