Journal of Cutaneous Pathology最新文献

Posttransplantation primary cutaneous T-cell lymphomas (PT-CTCL) are a rare complication of sustained immunosuppression in the posttransplant setting. When present, PT-CTCLs are typically EBV− and exhibit features of mycosis fungoides/Sézary syndrome or CD30+ lymphoproliferative disorders. We present a case of a 75-year-old individual who developed skin lesions 30 years after liver transplantation. Pathologic evaluation of the skin biopsy revealed involvement by a clonal, EBV+ T-cell population of gamma/delta lineage with no evidence of systemic disease. Comprehensive genomic profiling was performed, confirming focal one-copy loss of 6q23.3, altogether consistent with the extremely rare and unusual diagnosis of primary cutaneous EBV+ extranodal NK/T-cell lymphoma of gamma/delta T-cell lineage in the posttransplantation setting.

PRRX1-fused mesenchymal neoplasm is a recently identified, rare subcutaneous soft tissue neoplasm that is characterized by fusion of PRRX1 (exon 1) with NCOA1 (exon 13) in the majority of reported cases. Although initially considered to be fibroblastic, a possibility of neural or neuroectodermal differentiation has been suggested in a subset of cases. We report a 26-year-old female with a 4.0 cm painless mass located in the subcutis of the left thigh. Microscopically, the tumor was well-circumscribed and multinodular and was composed of relatively monomorphic ovoid to spindle cells arranged in loose fascicles, trabeculae, and cords within alternating myxoid and fibrous matrix, and vascularized stroma. Mitotic figures were scarce and necrosis was not observed. By immunohistochemistry, the neoplastic cells demonstrated focal co-expression of S100 protein and SOX10 and were negative for epithelial membrane antigen, smooth muscle actin, desmin, CD34, STAT6, HMB45, Melan-A, and MUC4. The expression of Rb1 was retained. Targeted RNA-sequencing identified a novel transcript fusion of PRRX1 (exon 1)::NCOA1 (exon 15), which was further confirmed by reverse transcription polymerase chain reaction and Sanger sequencing. The tumor was narrowly excised and no tumor recurrence or metastasis was identified after 13 months of follow-up. In summary, we report a new case of PRRX1-fused mesenchymal neoplasm, expanding the molecular genetic spectrum and providing further support for possible neural or neuroectodermal differentiation of this emerging soft tissue tumor entity.

Chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable success in treating various B-cell malignancies, redirecting T-cell cytotoxicity toward cancer cells. Despite its efficacy, CAR-T therapy is associated with potential risks, including cytokine release syndrome (CRS) and cytopenia. We present a case of a 69-year-old man with diffuse large B-cell lymphoma treated with axicabtagene-ciloleucel CAR-T therapy, who developed a rare and severe cutaneous toxicity resembling toxic epidermal necrolysis (TEN). The patient exhibited persistent fevers, CRS, and subsequent development of a widespread erythematous macular eruption, progressing to vesiculation with bullae. Notably, allopurinol-induced TEN was considered with the patient's recent exposure to allopurinol, although the onset and minimal mucosal involvement did not align with typical presentations of allopurinol-induced cases. The cutaneous reaction, distinct from typical SJS/TEN, showed minimal mucosal involvement and coincided with the cytokine release storm, differing from allopurinol-induced TEN. Despite the absence of guidelines, the patient was managed with systemic steroids, achieving significant improvement. This case expands the spectrum of CAR-T therapy-related cutaneous toxicities, highlighting the need for early recognition of histopathology and tailored management by dermatologists. Further understanding of these reactions is crucial for optimizing the safety profile of this groundbreaking immunotherapy.

Cutaneous metastasis is rare but may indicate an advanced internal malignancy or a recurrence of a previously treated one and is usually associated with a poor prognosis. They may also pose a diagnostic problem as the clinical manifestations are variable and non-specific, which could mimic other benign conditions. We report a case of a 48-year-old female who presented with a 4-year history of erythematous papules and vesicles on the trunk mimicking lymphangioma circumscriptum. Skin biopsy and immunohistochemistry were consistent with cutaneous metastasis from breast carcinoma. Cutaneous metastasis presents in a variety of patterns. A high index of suspicion and a low threshold for skin biopsy are paramount to the early diagnosis and treatment. A histopathologic evaluation will help identify the origin of the cutaneous metastasis and can significantly affect the outcome of the treatment.

Diffuse large B-cell lymphoma (DLBCL) is the most common and aggressive subtype of non-Hodgkin lymphoma. The overall risk of developing DLBCL is increased in patients with other lymphomas, such as mycosis fungoides (MF). In this report, we present an 81-year-old female with early-stage MF who simultaneously progressed to tumor stage, large-cell transformed (LCT) MF and developed a primary DLBCL in a lymph node (LN). She presented with a tumor on her leg and new lymphadenopathy in her right axilla. Skin biopsy of the tumor revealed infiltration of large atypical CD3⁺, CD4⁺, and CD30⁺ cells, and a smaller portion of CD8⁺ cells in the dermis, consistent with LCT MF. Biopsy of the axillary LN revealed diffuse sheets of CD20⁺, BCL-2⁺, c-MYC⁺, and CD10⁻ cells, highly suggestive of double expressor DLBCL. High-throughput sequencing revealed monoclonal T cells in the skin tumor and a monoclonal B-cell population in the LN. The above findings led to simultaneous diagnoses of LCT MF and nodal double expressor DLBCL. Our case demonstrates the importance of performing a full pathological workup in cutaneous T-cell lymphoma patients presenting with lymphadenopathy.

Fibroblastic connective tissue nevus (FCTN) is a rare, benign dermal mesenchymal lesion of fibroblastic and myofibroblastic lineage. We report a case of a 2-year-old male who presented with an 18-month history of an erythematous, asymptomatic, unchanging dermal plaque on the right medial frontal scalp. A punch biopsy showed a disorderly, bland, dermal fibroblastic spindle cell proliferation extending to the superficial subcutis. It stained positive for CD34, and concern for dermatofibrosarcoma protuberans was raised. However, FISH was negative for PDGFB rearrangement, and the constellation of findings was most consistent with FCTN. This case underscores the importance of distinguishing CD34⁺ mesenchymal tumors for both dermatologists and dermatopathologists. As these represent a rather diverse group of lesions with different biological behaviors, a knowledge of the differential diagnosis of these entities is critical for proper patient management.