Case report: Malignant epithelioid angiosarcoma in a Chinese female patient.

Perivascular epithelioid cell tumors (PEComas) are mesenchymal tumors that exhibit characteristic epithelioid or spindle cell morphology and typically grow around blood vessels. These tumors are characterized by the expression of melanocytic and smooth muscle markers, such as HMB-45, Melan-A, and smooth muscle actin, indicating a dual differentiation phenotype. PEComas are extremely rare diseases, and patients typically have a very poor prognosis. Here, we report a case of malignant cutaneous PEComa with pulmonary metastasis in a Chinese female and review relevant literature. The patient underwent surgical resection of a soft tissue tumor in the left upper arm under general anesthesia, and the subsequent pathological findings suggested a tumor with perivascular epithelioid cell differentiation (PEComa). The patient received adjuvant chemotherapy and radiotherapy after surgical resection, along with monitoring through computed tomography (CT) scans. Three months later, pulmonary metastasis was detected, but both the cutaneous PEComa in the left upper limb and the pulmonary metastatic lesions were stably controlled under active management and treatment. This is a rare case worth reporting and studying, and therefore, we conducted a long-term follow-up, and we hope to provide help for the clinical treatment of PEComa.

MPATH-Dx Version 2.0 Schema for Melanocytic Lesions: A Robust Tool for Standardized Diagnostic Reporting.

The new revised MPATH-Dx (Version 2.0) reporting schema for melanocytic lesions is presented herein. Principal changes include the simplification of the previous five-class Version 1.0 to a four-class hierarchy of melanocytic lesions to improve diagnostic agreement and to provide more explicit guidance in the management of patients. Version 2.0 also has clearly defined histopathological criteria for classification of Class I and II lesions now designated as low-grade (mild to moderate) atypia and high-grade (high-end moderate to severe) atypia, respectively. This new revised schema, also includes specific provisions for the less common WHO pathways to melanoma, provides guidance for classifying "intermediate" Class II tumors (melanocytomas), and recognizes a subset of pT1a melanomas with very low risk and possible eventual reclassification as a neoplasm falling short of fully-evolved melanoma.

Deep learning model shows pathologist-level detection of sentinel node metastasis of melanoma and intra-nodal nevi on whole slide images.

Introduction: Nodal metastasis (NM) in sentinel node biopsies (SNB) is crucial for melanoma staging. However, an intra-nodal nevus (INN) may often be misclassified as NM, leading to potential misdiagnosis and incorrect staging. There is high discordance among pathologists in assessing SNB positivity, which may lead to false staging. Digital whole slide imaging offers the potential for implementing artificial intelligence (AI) in digital pathology. In this study, we assessed the capability of AI to detect NM and INN in SNBs. Methods: A total of 485 hematoxylin and eosin whole slide images (WSIs), including NM and INN from 196 SNBs, were collected and divided into training (279 WSIs), validation (89 WSIs), and test sets (117 WSIs). A deep learning model was trained with 5,956 manual pixel-wise annotations. The AI and three blinded dermatopathologists assessed the test set, with immunohistochemistry serving as the reference standard. Results: The AI model showed excellent performance with an area under the curve receiver operating characteristic (AUC) of 0.965 for detecting NM. In comparison, the AUC for NM detection among dermatopathologists ranged between 0.94 and 0.98. For the detection of INN, the AUC was lower for both AI (0.781) and dermatopathologists (range of 0.63-0.79). Discussion: In conclusion, the deep learning AI model showed excellent accuracy in detecting NM, achieving dermatopathologist-level performance in detecting both NM and INN. Importantly, the AI model showed the potential to differentiate between these two entities. However, further validation is warranted.

Pancreatitis, panniculitis, and polyarthritis syndrome in a dog with hyalinizing pancreatic adenocarcinoma.

A 10-y-old spayed female Cavalier King Charles Spaniel dog was presented to the Veterinary Teaching Hospital because of recurrent chronic abscesses on the distal pelvic limbs, fever, lethargy, lameness of unknown etiology, and chronic pancreatitis. Sterile nodular panniculitis was diagnosed after an extensive workup, and the dog initially responded to immunosuppressive therapy, but relapse and spread of cutaneous lesions and acute lameness occurred after 11 mo, and euthanasia was elected. Postmortem examination confirmed hyalinizing pancreatic adenocarcinoma with pancreatitis, panniculitis, polyarthritis (PPP), and osteomyelitis. Histopathology and bacterial and fungal cultures were supportive of a sterile process, specifically the PPP syndrome, which is a rare, potentially life-threatening, systemic manifestation of pancreatic disease in both people and animals. To our knowledge, a clinicopathologic description of a hyalinizing pancreatic adenocarcinoma associated with this rare syndrome has not been reported previously in a dog.

Facial Sebaceous Hyperplasia in an Adolescent With Hypohidrotic Ectodermal Dysplasia.

We report on a 13-year-old boy diagnosed with hypohidrotic ectodermal dysplasia (HED) due to a pathogenic variant in ectodysplasin A (EDA). He exhibited multiple whitish, millimetric papules clustered on the nasal ala, forehead, temporal, and zygomatic arch areas. Histological examination revealed numerous hyperplastic sebaceous lobules within the upper dermis. The occurrence of sebaceous papules in this distribution among HED patients has rarely been reported. An association with the blockage of the Wnt/ß-catenin pathway due to EDA malfunction has been speculated.

Crusted plaques on the face.

Facial neutrophilic dermatosis is a relatively recent and rare entity. Herein, we report an original case with a clinical appearance of crusty pyoderma gangrenosum and limited face involvement, classifying it as neutrophilic dermatosis (ND) of the face. The latter is an infrequent entity and forms part of the ND spectrum. The few reported cases in the literature are characterized by a restricted distribution on the face, as in our case. Nevertheless, this entity remains controversial: some consider it a variant of Sweet's syndrome; others see it as a truly independent entity. Matthews et al. reported an association between ND of the face, as in the case of our patient with a crusty appearance, and ulcerative colitis. Our observation and that of Matthews et al. underline the wide and varied potential for the clinical presentation of this entity.

A decision support system for the detection of cutaneous fungal infections using artificial intelligence.

Cutaneous fungal infections are one of the most common skin conditions, hence, the burden of determining fungal elements upon microscopic examination with periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) stains, is very time consuming. Despite some morphological variability posing challenges to training artificial intelligence (AI)-based solutions, these structures are favored potential targets, enabling the recruitment of promising AI-based technologies. Herein, we present a novel AI solution for identifying skin fungal infections, potentially providing a decision support system for pathologists. Skin biopsies of patients diagnosed with a cutaneous fungal infection at the Sheba Medical Center, Israel between 2014 and 2023, were used. Samples were stained with PAS and GMS and digitized by the Philips IntelliSite scanner. DeePathology® STUDIO fungal elements were annotated and deemed as ground truth data after an overall revision by two specialist pathologists. Subsequently, they were used to create an AI-based solution, which has been further validated in other regions of interests. The study participants were divided into two cohorts. In the first cohort, the overall sensitivity of the algorithm was 0.8, specificity 0.97, F1 score 0.78; in the second, the overall sensitivity of the algorithm was 0.93, specificity 0.99, F1 score 0.95. The results obtained are encouraging as proof of concept for an AI-based fungi detection algorithm. DeePathology® STUDIO can be employed as a decision support system for pathologists when diagnosing a cutaneous fungal infection using PAS and GMS stains, thereby, saving time and money.

Dermal melanoma with plasmacytoid differentiation in a dog.

A 10-y-old spayed female Staffordshire Terrier dog was evaluated because of a cutaneous left ear base mass. Cytology revealed sheets of cells with anisocytosis and anisokaryosis, round-to-oval or plasmacytoid cytoplasm, and round, central, or eccentric nuclei; binucleate cells were present. Cytologic findings were consistent with a round cell tumor (plasmacytoma or agranular mast cell tumor), amelanotic melanoma, or anaplastic carcinoma. Histologically, neoplastic cells were polygonal to elongate, with round-to-oval nuclei and prominent nucleoli and arranged in sheets and nests on a fibrovascular stroma. Neoplastic cells with plasmacytoid morphology (round, glassy, eosinophilic cytoplasm with eccentric nuclei) were present in ~30% of the neoplasm. There were 18 mitoses in 2.37 mm2 (10 FN22/40× fields). Neoplastic cells had cytoplasmic immunolabeling for melan A and PNL2 and no immunolabeling for AE3/1 and MUM1, consistent with a dermal melanoma with plasmacytoid differentiation. The patient was re-evaluated ~1 mo after the first biopsy because of local recurrence of the original mass and new masses on the interscapular area and right elbow; these neoplasms were histologically identical to the original submission, plus scattered neoplastic cells in the new masses contained brown cytoplasmic pigment. The dog was euthanized because of swelling and hemorrhage of the tumors and right pelvic limb lameness. Our findings were consistent with a dermal melanoma with plasmacytoid features that were similar to human plasmacytoid melanoma, a rare variant of human melanoma that is diagnostically challenging as it may mimic a plasmacytoma.

Idiopathic Eruptive Macular Pigmentation with Papillomatosis: A Common but Underdiagnosed Entity.

Idiopathic Eruptive Macular Pigmentation (IEMP) is an uncommon and possibly underdiagnosed dermatosis. It manifests as asymptomatic pigmented macules over the face, trunk and proximal extremities among children and adolescents. Degos et al. first documented this condition in 1978, unveiling its distinct characteristics. The macules, initially dark brown-black, naturally diminish over several months to years, with no lasting pigmentation or scarring. In this report, we highlight the case of a 14-year-old girl displaying all the distinctive traits of IEMP.

A case of NONO::TFE3 cutaneous epithelioid and spindle cell tumor with local recurrence after complete excision.

Mesenchymal tumors may display morphologic and immunohistochemical overlap with melanocytic tumors, presenting a pitfall for misdiagnosis. We report a 62-year-old woman who presented with a recurrent dermal and subcutaneous tumor over the Achilles tendon 15 years following complete excision. Both the primary and the recurrent tumors were characterized by nests and sheets of epithelioid and spindle cells with eosinophilic cytoplasm and uniform ovoid nuclei. The tumor was positive for S100, SOX10, HMB45, cathepsin K, and p63 (weak), while negative for Melan-A, MiTF, smooth muscle actin, and desmin. Gene fusion analysis of the recurrent tumor revealed a NONO::TFE3 fusion which has been recently reported in two similar cutaneous cases. Our case highlights the potential of a NONO::TFE3 cutaneous epithelioid and spindle cell tumor to recur after a prolonged disease-free interval without evidence of high-grade transformation or distant metastasis. Our findings support its classification as a cutaneous mesenchymal neoplasm of intermediate malignancy.

Revisiting X-linked congenital ichthyosis.

X-linked recessive ichthyosis (XLI) is a hereditary skin disease characterized by generalized dryness and scaling of the skin, with frequent extracutaneous manifestations. It is the second most common type of ichthyosis, with a prevalence of 1/6,000 to 1/2,000 in males and without any racial or geographical differences. The causative gene for XLI is the steroid sulfatase gene (STS), located on Xp22.3. STS deficiency causes an abnormal cholesterol sulfate (CS) accumulation in the stratum corneum (SC). Excess CS induces epidermal permeability barrier dysfunction and scaling abnormalities. This review summarizes XLI's genetic, clinical, and pathological features, pathogenesis, diagnosis and differential diagnoses, and therapeutic perspectives. Further understanding the role of the STS gene pathogenic variants in XLI may contribute to a more accurate and efficient clinical diagnosis of XLI and provide novel strategies for its treatment and prenatal diagnosis.

A case of erythema ab igne with histopathological features resembling keratosis lichenoides chronica.

This case describes a pediatric patient with a history of ichthyosis vulgaris and global anhidrosis who was diagnosed with erythema ab igne (EAI), a rare dermatosis resulting from chronic heat exposure. After developing progressive, reticulated brown patches on his extremities and abdomen, extensive diagnostic investigations were conducted to rule out autoimmune, vascular, and genetic etiologies. Bloodwork was unrevealing and biopsies showed histologic features closely resembling keratosis lichenoides chronica. Ultimately, after discovering the patient had prolonged exposure to a space heater, the diagnosis of EAI was made. This case underscores the diagnostic challenges in pediatric EAI cases and emphasizes the importance of careful history taking as part of a comprehensive evaluation.