An incidental perianal pseudolymphoma

Benign intralymphatic proliferation of atypical T-cell lymphoid blasts is a rare benign entity with only a handful of cases reported in the literature. Thought to be a reactive lymphoid proliferation, it represents a potential diagnostic pitfall for pathologists, as the presence of large atypical lymphocytes within lymphovascular spaces raises suspicion for intravascular lymphoma. This report presents a case with benign intralymphatic proliferation of atypical T-cell lymphoid blasts within a solitary perianal ulcer from a healthy 28 year old female. Histology showed ulcerated squamous mucosa with underlying inflamed granulation tissue. Lymphovascular spaces were noted to be dilated and filled with medium to large atypical lymphoid cells with irregular vesicular nuclei and amphophilic cytoplasm. Immunohistochemistry demonstrated the atypical lymphoid cells to be T cells (CD3 and CD5 positive) with patchy positivity for CD30. The atypical T cells were found to be contained within D2-40 positive lymphatic spaces and not intravascular. The patient had no other lesions and full blood examination showed no evidence of leukaemia. In summary, this case report presents a rare benign reactive entity which is a potential mimic for intravascular lymphoma. It will review the literature and discuss the proposed diagnostic criteria and differential diagnoses.