April 2003: 55-year-old male with necrotic pontine lesion.

The April Case of the Month (COM). A 55-year-old male with history of diabetes mellitus presented with progressive loss of sensitivity on the left side of the body and horizontal diplopia. Symptoms appeared after a right basal pneumonia one month before admission. A CT scan showed an large inoperable lesion in the pons. The patient was treated with corticoids. One week later, the patient showed general deterioration. The fifth and sixth right cranial nerves were affected. Ataxia and disorders in swallowing were also present. A second CT scan showed that the pontine mass had become larger. The patient died 7 days after his admission and the autopsy was limited to CNS. The right middle cerebellar peduncle showed a 2-cm well-defined white brownish necrotic lesion that extended to the pons and periventricular gray matter. Microscopic examination revealed toxoplasmosis, which was confirmed by immunohistochemical studies. The brain tissue was negative for HIV by PCR. Toxoplasmosis is a well-known complication of AIDS, and has been reported in post-transplant patients as well, but only a few reports of toxoplasmosis in diabetics have been reported.

Fine-needle aspiration of chromophobe renal-cell carcinoma metastatic to the thyroid gland.

Chromophobe renal cell carcinoma is an unusual variant of renal carcinoma that has less aggressive behavior than clear cell carcinomas. There are few documented cases of metastases, none of which occurred in the thyroid gland. A case is presented of chromophobe renal cell carcinoma metastatic to the thyroid eight years after right nephrectomy, suspected by FNA-biopsy and confirmed histologically. Although metastases of chromophobe renal cell carcinoma are rare, they may also present in thyroid, even many years after primary tumor diagnosis, just like clear cell carcinomas. Even though the FNA cytology of chromophobe renal cell carcinoma has distinctive features, in the context of the thyroid, it can be mistaken for a primary tumor of that organ. In our case, the history of a previous renal tumor was essential in suggesting a metastatic lesion, and histologic and ultrastructural features allowed its precise identification.

Thymoma associated with CD4+ lymphopenia, cytomegalovirus infection, and Kaposi's sarcoma.

A case of thymoma with associated opportunistic infections, CD4/CD8 T-lymphocyte imbalance, low CD4-positive T-lymphocyte counts and Kaposi's sarcoma (KS) without HIV infection is reported. Cytomegalovirus inclusions were identified in the nuclei of some KS spindle and endothelial cells. It is known that KS has a high prevalence in AIDS patients and has occasionally been associated with other causes of immunosuppression. In previous studies, coexisting KS and thymoma were related to myasthenia gravis, corticosteroid treatment and excess CD8-positive T-lymphocyte counts. More recently an imbalance between CD4 and CD8 positive T lymphocytes has been identified in association with thymoma. The present case suggests that there may be a relationship between thymoma, CD4-positive lymphopenia, and KS.