[Pigmented or hemosiderotic atypical fibroxanthoma]. / Fibroxantoma atípico pigmentado o hemosiderótico.

Pigmented atypical fibroxanthoma is a rare variant of atypical fibroxanthoma and is characterized by extensive areas of hemorrhage, erythrophagocytosis, and hemosiderin accumulation in the cytoplasm of the neoplastic cells. It affects elderly individuals and presents as irregularly pigmented, dome-shaped nodules or plaques on areas of skin exposed to the sun. We present a case of pigmented atypical fibroxanthoma on the cheek of an 81-year-old man. Six years after excision of the lesion, the patient remains in complete remission, with no signs of residual tumor or metastasis. The 9 cases of pigmented atypical fibroxanthoma reported in the literature are reviewed, and the histopathological features and differential diagnosis are discussed.

[Methotrexate-associated lymphoproliferative disorder presenting as oral ulcers in a patient with rheumatoid arthritis]. / Ulceras orales como manifestación clínica de proceso linfoproliferativo asociado a metotrexato en una paciente con artritis reumatoide.

Methotrexate-associated lymphoproliferative disorders are a heterogeneous group of lymphoid proliferations or lymphomas that develop in patients with autoimmune diseases treated using methotrexate. These lymphoproliferative disorders are often associated with Epstein-Barr virus infection and occasionally regress after the withdrawal of methotrexate therapy. The lymphoproliferative disorder in this case was diffuse large B-cell lymphoma, unusually presenting as oral ulcers in a 79-year-old woman on treatment with methotrexate for longstanding rheumatoid arthritis. Latent membrane protein 1 positivity was detected by immunohistochemistry and Epstein-Barr-virus encoded small RNA positivity by chromogenic in situ hybridization. Clonality was confirmed by immunohistochemistry (kappa light-chain restriction), polymerase chain reaction (monoclonal immunoglobulin H gene rearrangement), and capillary electrophoresis (GeneScan). Staging procedures were negative. Withdrawal of methotrexate therapy led to complete remission within 6 weeks, and the patient is alive and disease-free 18 months after the diagnosis was made. The oral cavity is not often involved in the initial presentation of methotrexate-associated lymphoproliferative disorders, and presentation with intraoral ulcers is very rare. We have performed a review of the literature on methotrexate-associated lymphoproliferative disorders presenting as ulcers in the oral cavity.

Neurofibroma with psammoma bodies.

Neurofibromas are benign tumours of the nerve sheath. Histologically they vary depending on their contents of cells, myxoid stroma and collagen. A 41-year old male with radicular pain had a tumour involving the posterior chest wall. Microscopically it resulted to be a neurofibroma with abundant psammoma bodies. Although these bodies are very frequent in some neoplasias, to our knowledge they have not been described in neurofibromas to date.