Journal of Cutaneous Pathology最新文献

Granuloma faciale (GF) is a rare, benign, chronic dermatosis that typically presents as reddish-brown to violaceous plaques on the face. Here, we report the first documented case of GF arising in association with both squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). A 79-year-old man with a history of several non-melanoma skin cancers presented with new lesions on the right cheek and ear. Biopsies confirmed GF on the cheek and SCC on the ear, with adjacent inflammatory infiltrates also consistent with GF. Additionally, subsequent Mohs micrographic surgery revealed a distinct, coexisting BCC within the same lesion. To our knowledge, only two cases of GF co-occurring with BCC have been reported, and none with concurrent SCC's. This case highlights the diagnostic complexity of GF in patients with a history of skin cancer and underscores the importance of histopathologic confirmation when evaluating persistent or overlapping lesions. The unique triad of GF, SCC, and BCC reflects potential inflammatory or immune-mediated mechanisms linking chronic dermatoses with carcinogenesis and warrants further investigation.

Immunohistochemistry with T-cell receptor β-chain constant domain 1 (TRBC1) has been reported to be helpful in distinguishing between a clonal or reactive process. TRBC1 interpretation can be challenging in cases with a low proportion of neoplastic T-cells and high numbers of reactive T-cells. In this study we evaluated TRBC1 immunohistochemistry retrospectively on four cases with known T-cell receptor clonality results by polymerase chain reaction that were clinically categorized as hypopigmented mycosis fungoides. TRBC1 immunohistochemistry was defined as monotypic-negative (TRBC1 < 25%, i.e., < 1 in 4 positive lymphocytes) or monotypic-positive (TRBC1 > 75%, i.e., > 3 of 4 lymphocytes positive), or non-monotypic (TRBC1 > 25% and < 75%). Immunohistochemical results when assessing TRBC1 monotypic expression in the intraepidermal component in all four cases were concordant with T-cell receptor clonality assays. Assessing TRBC1 expression with particular focus on the intraepidermal component may be helpful as a useful data point when evaluating for hypopigmented mycosis fungoides.

Background: Drug-induced hyperpigmentation accounts for 10%-20% of acquired pigmentary disorders and can be misdiagnosed for other causes such as melasma, post inflammatory changes, or heavy metal deposition. Kratom (Mitragyna speciosa), a Southeast Asian plant with an opioid-like profile, has been increasingly used in the United States for several conditions such as pain, mood disorders, and opioid withdrawal. While neuropsychiatric and liver toxicity adverse effects are documented, hyperpigmentation, and skin changes remain poorly recognized.

Case presentation: We describe a 38-year-old female with a history of Hashimoto's thyroiditis and seizure disorder who developed a progressive blue-gray hyperpigmentation over 3 years. The hyperpigmentation was initially confined to the nose and subsequently spread to the face, neck, chest, upper back, and arms. It was initially diagnosed and treated as melasma without improvement. Skin biopsies revealed basal layer hyperpigmentation and dermal melanophages. Fontana-Masson staining demonstrated an admixture of black melanin granules and distinct red-brown intracytoplasmic pigment, consistent with Kratom-associated drug deposition. These findings were consistent with drug-induced hyperpigmentation. A comprehensive medication review history excluded commonly implicated drugs. Upon further questioning, the patient disclosed prior use of kratom tea for approximately 18 months, which was discontinued around the time of the clinical presentation.

Conclusion: This case highlights the importance of thorough exposure history, including herbal supplements, in the workup of atypical hyperpigmentation and highlights novel histopathological features of Kratom-associated hyperpigmentation that expand the current understanding of drug-induced cutaneous changes.

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors typically arising on sun-damaged skin of the head and neck in elderly patients. PDS is a more aggressive tumor but with similar demographics, cellular morphology, immunohistochemical features, and genetic findings. The histopathologic diversity and lack of specific immunohistochemical markers for these entities increase the risk of misdiagnosis. To our knowledge, osteoid matrix production has been noted previously in only one case of PDS. We present three additional cases of AFX/PDS with osseous metaplasia, all of which were from the head of elderly patients (91-93 years old). No case recurred or metastasized, thus underscoring the importance of distinguishing this entity from other primary or metastatic tumors with osseous differentiation or metaplasia.

Background: A dermatofibroma is a common benign cutaneous neoplasm composed of variable combinations of fibroblasts, histiocytes, and coarse collagen fibers. The aneurysmal/hemosiderotic (HDF/ADF) subtypes have characteristic pseudo-vascular spaces with hemosiderin-laden histiocytes and reactive spindled and epithelioid cells. These subtypes histologically can resemble melanocytic and vascular tumors, sometimes necessitating the use of immunohistochemical and histochemical stains to appropriately differentiate these entities. To our knowledge, Fontana-Masson staining has not previously been investigated in HDF/ADF.

Methods: A search of the SLUCare Dermatopathology Laboratory Information System was performed to identify cases signed out as aneurysmal and/or hemosiderotic dermatofibroma. These were then stained with Fontana-Masson stain and SOX-10 or S100 protein and evaluated by two board-certified dermatopathologists.

Results: A total of 79 cases were included, 48 females and 31 males aged between 12 and 84 years. Ninety-five percent of ADF and 98% of HDF cases were positive for Fontana-Masson stain. SOX-10 or S100 protein stain was negative in all cases.

Conclusions: This study demonstrates that HDF/ADF stain with Fontana-Masson suggests the presence of melanin in these dermatofibroma subtypes, although Fontana-Masson is not entirely specific for melanin. These findings indicate that ADF/HDF are often highlighted by Fontana-Masson, suggesting that Fontana-Masson may not be a reliable tool for distinguishing HDF/ADF from melanocytic lesions. SOX-10/S100 may be useful in differentiating HDF/ADF from melanocytic lesions.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, highly aggressive hematologic malignancy characterized by cutaneous involvement with potential dissemination to peripheral blood, bone marrow, lymph nodes, or extranodal sites. We present the first documented case of BPDCN exhibiting complex epigenetic dysregulation in a 54-year-old female who developed rapidly progressive purpuric lesions on the trunk, diagnosed via skin biopsy and immunohistochemistry. Cytogenetic analysis revealed triple molecular aberrations including a t(1;6) (p31;q25) translocation, a TET2 frameshift deletion (44.1% VAF), and a KDM6A missense mutation (c.262G>A, 46.6% VAF). The patient died within 6 months post-diagnosis, suggesting that this aggressive clinical course may be associated with a novel clinicogenetic subtype of BPDCN.

Background: Leukocytoclastic vasculitis (LCV) and microvascular occlusion (MVO) are distinct histopathologic patterns underlying dermatologic diagnoses of purpura. This study explores the potential of attention-based artificial intelligence (AI) models to enhance diagnostic accuracy and provide interpretable insights in differentiating these conditions, serving as a proof of concept for the application of explainable AI in dermatopathology.

Methods: We compared the performance of two attention-based AI models, clustering-constrained-attention multiple-instance learning (CLAM) and attention multiple instance learning (MIL), in analyzing whole slide images of LCV and MVO cases. The models were trained and evaluated using a cohort of 69 biopsies. Performance metrics included precision, recall, accuracy, AUROC, and F1 score. Attention-based heatmaps were generated to highlight diagnostic regions and reveal histopathologic patterns.

Results: The CLAM model outperformed the attention MIL model across all evaluation metrics. Generated heatmaps effectively highlighted key diagnostic regions, including subtle areas of occlusion in the superficial papillary dermis of MVO cases.

Conclusions: This study demonstrates the potential of attention-based AI models to improve diagnostic accuracy and provide interpretable insights in differentiating LCV and MVO. The use of explainable AI and heatmaps offers a valuable tool for pathologists, enhancing their ability to identify and understand subtle histopathologic patterns.

Molecular profiling has revolutionized the field of soft tissue pathology, enhancing diagnostic precision and treatment strategies. The integration of molecular analysis and immunohistochemistry has been crucial for classifying diagnostically challenging acral mesenchymal neoplasms. Herein, we report the first documented case of an acral mesenchymal spindle cell neoplasm harboring an HMGA2::NCOA2 fusion. The neoplasm presented as a slow-growing verrucous papule on the right thumb of an 18-year-old female. Histological examination revealed spindled cells of varying cellularity with intervening sclerotic collagen and dilated vasculature. The cells had patchy S100 and focal GLUT-1 reactivity but were negative for CD34, EMA, Sox-10, Pan-TRK, p63, CKAE1/3, MUC4, ALK, Factor 13A, actin, desmin, and ERG. Given the unusual morphology and non-diagnostic immunohistochemical profile, the specimen was sent for additional molecular profiling. Next-generation sequencing revealed a novel in-frame HMGA2::NCOA2 fusion. The tumor was likely benign, with 4 mitoses per 10 high-powered fields (HPF), but was excised due to the unpredictable behavior of the fusion. As the first known case to date with this fusion, these findings contribute to the emerging research on genomic testing in acral soft tissue tumors. Additional cases and longer clinical follow-up are needed to better characterize the novel HMGA2::NCOA2 fusion.