No abstract

The results of the current study show that CD44v6 is localized differently in fetal and adult lung, suggesting a difference in function. In the fetal lung, it may modulate growth factors important in morphogenesis and maturation. In the adult nonneoplastic lung, CD44v6 is associated with stem cells, namely basal cells and type 2 pneumocytes, and may act to anchor these cells to the matrix and be important in migration during repair or neoplasia. In addition, CD44v6 expression is maintained throughout tumorigenesis in squamous cell carcinoma and bronchioloalveolar cell carcinoma, suggesting a histogenetic relationship between the stem cells and the respective tumors. Conversely, most neuroendocrine tumors and the cells of the dispersive neuroendocrine system do not express CD44v6, implying a separate histogenetic lineage in these tumors.

A 49-yr-old homosexual man with acquired immunodeficiency syndrome presented with a left-sided neck mass. He was found to have a firm goiter. He was clinically euthyroid, but had laboratory evidence of primary hypothyroidism. Radioactive iodine scan of the thyroid showed homogeneous uptake over an enlarged right lobe and absence of uptake over the left lobe. Two fine needle aspiration biopsies of the thyroid revealed the presence of Pneumocystis carinii (P. carinii) organisms on the Gomori's methenamine silver strain. After courses of iv and oral therapy with trimethoprim-sulfamethoxazole, a third fine needle aspiration biopsy failed to reveal any organisms. A repeated radioactive iodine scan of the thyroid showed return of uptake over the left lobe. Thyroid function tests normalized with levothyroxine, and the goiter decreased in size. To our knowledge, this is the first report of hypothyroidism associated with P. carinii infection of the thyroid. P. carinii infection should be considered in the differential diagnosis of human immunodeficiency virus infected individuals presenting with cold thyroid nodules. Fine needle aspiration biopsy is a valuable tool in assessing these patients.

To establish the indications for splenectomy in patients with human immunodeficiency virus (HIV) infection we retrospectively analyzed 12 patients who underwent splenectomy. Patients with HIV infection who had immune thrombocytopenic purpura (ITP) were excluded as they had no splenomegaly and a definite indication for splenectomy exists in some of these patients. All 12 patients were anemic; 6 were thrombocytopenic and 6 leukopenic. All patients had splenomegaly and all were febrile. At surgery 3 patients were found to have Mycobacterium avium intracellulare (MAI) infection; 2 had splenic abscess due to Salmonella group D; 1 each had cytomegalovirus (CMV) splenitis and localized Kaposi's sarcoma (KS) of the spleen. No definite histopathologic diagnosis could be made in five patients, all of whom had evidence of extramedullary hematopoiesis. The degree of splenic enlargement did not correlate with the outcome. Both clinical and hematologic improvements were achieved in patients with splenic abscess and in patients who had splenomegaly, anemia, and thrombocytopenia. The presence of either of these findings constitutes an indication for splenectomy. Anemia and/or leukopenia without thrombocytopenia failed to improve; the presence of MAI and active CMV infection also resulted in failure. The presence of either of these conditions may be considered a contraindication to splenectomy.

We describe a unique association of histiocytic necrotizing lymphadenitis (Kikuchi's disease) and chronic lymphocytic (Hashimoto's) thyroiditis in a patient who presented with significant cervical lymphadenopathy and a goiter. This case illustrates the value of lymph node biopsy combined with the fine needle aspiration of the thyroid in determining the nature of the relationship between the goiter and lymphadenopathy.