A Case of Primary Cutaneous T-Follicular Helper Cell Lymphoma, Follicular-Type.

This is a case of primary cutaneous T-follicular helper cell lymphoma, follicular-type. A 99-year-old woman was detected with cutaneous mass located in left greater trochanter area and buttock, which was suspected to be malignant lymphoma. Computed tomography revealed few regional lymph node enlargement. Skin biopsy was performed for diagnosis. Pathologically, diffuse and dense proliferation of medium-sized atypical lymphocytes was observed proliferating with a vague nodular pattern. The immunohistochemical analysis presented that atypical lymphocytes composing vague nodular lesion were positive for CD3, CD4, PD-1, ICOS, BCL6, and CXCL13. Additionally, diffuse medium-sized B-cell proliferation was also observed. The monoclonality of T-cell receptor-gamma and IgVH was confirmed by polymerase chain reaction. Here we described a primary cutaneous case of FTCL. In the 5th edition of the WHO classification, TFH lymphoma is limited to lymph node and there is no consensus regarding the management of extranodal TFH lymphoma. Further accumulation of extranodal counterpart of the cases and clinicopathological examination of extranodal and nodal lesions is desired.