[Immunoproliferative small intestinal disease. Report of a case with immunohistochemical and ultrastructural study].

The clinico-pathological characteristics of a 22 years old mestizo mexican patient with immunoproliferative small intestinal disease (IPSID) are described. The patient coursed with chronic diarrhea, malabsorption, and a 30 kg weight loss. The laboratory tests revealed hypokalemia, hypocalcemia, hypoalbuminemia and decreased levels of immunoglobulins. The histological changes in the endoscopic biopsies included a dense lymphoplasmacytic infiltrate in the lamina propria that produced vellosity blunting and distortion of the crypts. The immunohistochemical analysis disclosed that almost every cell was positive to heavy chains and negative to light chains. The radiological studies showed thickening of the intestinal folds and mesenteric adenomegalies. In the full thickness biopsy of the yeyunum, in addition to the lymphoplasmacytic infiltrate, a high grade malignant lymphoma infiltrating the regional lymph nodes was documented. An ultrastructural study revealed viruses that resembled the morphology described for the Epstein-Barr virus. The main clinico-pathological findings of other eight mexican patients with IPSID previously reported are commented. It is concluded that the IPSID is a rare disease in our country but it can be found sporadically.