Benign atypical intralymphatic CD30+ T-cell proliferation is an extremely rare reactive lymphoid proliferation that may mimic malignancy owing to the presence of atypical lymphocytes within lymphatic vessels 1. We report a case with extensive cutaneous manifestations following severe infection. A 61-year-old man with a complex medical history, including a liver transplant at age 47 for hepatitis C and cirrhosis, end-stage renal disease requiring hemodialysis since age 60, and recurrent cholangitis, was emergently admitted for fever and shock during dialysis. He was diagnosed with cholangitis and septic shock, and treatment with meropenem and teicoplanin was initiated. Four days after admission, although his sepsis was under control, diffuse edema and erythematous plaques, progressing to bullae and purpura, appeared on his trunk and bilateral lower extremities (Figure 1a,b). Laboratory investigations at that point revealed elevated white blood cell count, and elevation of C-reactive protein. Soluble interleukin-2 receptor level was as high as 1996 U/mL, and LDH level was not elevated. The blood cultures were negative. Computed tomography scans showed widespread subcutaneous edema and fat stranding in the limbs and trunk, without evidence of abscess, gas formation, deep fascial involvement, or any lymphadenopathy. A skin biopsy was performed, and empirical intravenous methylprednisolone at 60 mg/day was initiated along with continued antibiotics. Histopathological examination revealed subepidermal blistering without epidermal necrosis or vacuolar degeneration (Figure 1c). The superficial dermis contained atypical medium-sized lymphocytes filling the dermal vessels (Figure 1d). Immunohistochemistry demonstrated that these cells were positive for CD3, CD4, CD5, CD25, and partially positive for CD30, while being negative for CD7, CD8, CD56, and EBER-ISH. MIB-1 index was high, and D2-40 staining showed that these cells were in the lymphatic vessels (Figure 1e). Monoclonal TRG gene rearrangement was not detected by PCR analysis. Based on these findings, a diagnosis of benign atypical intralymphatic CD30+ T-cell proliferation was made. Although it remained unclear whether it was caused by the antibiotic, the skin lesions subsided rapidly within 2 weeks after methylprednisolone initiation. Benign atypical intralymphatic CD30+ T-cell proliferation is characterized by the presence of medium-to-large-sized CD30-positive T lymphocytes within lymphatic vessels 1-3. Clinically, cases presenting with various symptoms such as erythema, erosions, nodules, and purpura have been reported. Key diagnostic clues include a favorable prognosis, the absence of EBV involvement, and lack of monoclonal T-cell receptor gene rearrangement. Although the exact cause and mechanism of lymphocyte localization remain unclear, given CD25 expression and the presence of background inflammatory disorders in our case and previous cases, responsive proliferation of activated T cells may be the true nature of this condition 3, 4. Histopathological differentiation from aggressive intravascular lymphomas, such as intravascular NK/T-cell lymphoma or intravascular anaplastic large cell lymphoma (ALCL), is essential 5. Intravascular NK/T-cell lymphoma typically exhibits CD56 positivity, EBV association, and poor prognosis, while intravascular ALCL usually shows CD8 + CD30+ cells with cytotoxic markers. In our case, polyclonality and the absence of systemic lymphoma or aggressive clinical course strongly supported a benign process. Further case accumulation is needed to elucidate the etiology and pathogenesis of this entity. Tomomitsu Miyagaki is an editorial board member of Journal of Dermatology and a co-author of this article. To minimize bias, they were excluded from all editorial decision-making related to the acceptance of this article for publication. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
Hisamoto et al. (Tue,) studied this question.