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The capacity of a recombinant glutathione S-transferase from Schistosoma mansoni (rSm28GST) to vaccinate primates (Erythrocebus patas) against a heterologous infection with Schistosoma haematobium has been tested. Two injections of the purified molecule with Muramyl-Di-Peptide (MDP) as adjuvant resulted in a high level antibody response in the five immunized animals and in a significant reduction in worm fecundity compared to the controls which received adjuvant alone. Mean levels of daily egg excretion in urine an faeces were reduced by respectively 55% and 74% although perfusion revealed that worm burdens were similar in both groups. The protective effect was long lasting since it was maintained up to the end of the experiment, 42 weeks after infection. Hatching rates and the numbers of intra-uterine eggs were also significantly affected by the vaccination. Tissue eggs were also drastically diminished in the urogenital system (-80%) but the reduction was not statistically significant. One animal was not protected by the immunization. There was a good correlation between parasitological data and the intensity of bladder lesions assessed by microscopic examination. Polypoid formations together with an intense exudation of the lamina propria were frequently seen in the controls but rarely in the vaccinated group where formation of scar tissue was predominant. These results underline the vaccine potential of the recombinant Sm28GST as a possible valuable prophylactic tool for the control of egg-induced pathology and transmission of African schistosomes.

A series of eight plasma cell granulomas of the lung were examined. Their clinical, pathologic, and immunohistochemical characteristics as well as the ultrastructural features of one case are in agreement with those found in the literature. One patient died after a surgical intervention complicated by invasion of pulmonary veins. This led to a search for vascular injuries in the other cases. On the whole, of eight cases, two showed vascular invasions at a distance, five (including the preceding ones) showed invasion of medium-sized blood vessels in the peripheral parts of the lesion, and three showed older invasions in their center; only two had no vascular lesions. To the authors' knowledge, vascular invasion at a distance has been reported only once to date. An inflammatory origin for these cytologically benign lesions remains possible, although a striking resemblance with intravascular fasciitis can also be shown. These lesions should be treated by radical and precocious surgery.

The authors report on a case of dentigerous cyst associated with odontogenic adenomatoid tumor in an 8-year-old black Nigerian boy. Both the cyst and the tumor contained melanocytes and melanin-laden epithelial cells. To their knowledge this is the first reported case of melanotic follicular cyst and adenomatoid tumor. A review of the literature revealed that melanin is rarely found in odontogenic lesions. Since the neural crest influence on the development of odontogenic tissues is well established, the occurrence of melanocytes in these tissues is not surprising. A racial predisposition may be present; black patients predominated in the 15 reported cases of melanotic odontogenic lesions. Cancer 66:786-788, 1990.ELANIN is rarely found in odontogenic lesions.M Melanotic neuroectodermal tumor of infancy is often reported as the only jaw tumor where this pigment appears.' For this reason it is also known as melanoameloblastoma, a misnomer because it is not related to the enamel organ, but it is rather of neural crest derivation.' However the neural crest interacts in the development of teeth;3 it is thus not surprising that melanocytes can occur in truly odontogenic tissues. An unusual case was encountered in a black Nigerian boy with a melanotic odontogenic cyst and tumor. To our knowledge this lesion has not been reported previously. Materials and MethodsThe surgical specimens were fixed in formalin and stained with hematoxylin and eosin, Prussian blue, and the Fontana-Masson method. Immunohistochemical methods used antibodies to vimentin and S-100 protein (Dako Corporation, Santa Fe, CA). Results Clinical DataThe 8-year-old patient was seen in the Stomatology Center of Niamey for a tender swelling of the right cheek. Dental examination showed that the right mandibular cuspid and both premolar teeth had not erupted. The lateral incisor was displaced toward the midline. The facial side of the gum was swollen and bluish. Radiographs showed a 5.9 X 3-cm radiolucent bone lesion centered on the cuspid area (Fig. 1 ). The facial mandibular cortex was thin, but the inner cortex was normal. The lesion looked well circumscribed. The unerupted cuspid lay in its floor and the first premolar, against its posterior wall. Treatment consisted of incising the cyst, which was filled with a pale yellow fluid, followed by curettage of the walls and resection of the cuspid, lateral incisor, and first premolar. One month later, radiographs showed a homogeneous radiolucent area in the curettage field. The patient did not return for follow-up. PathologyThe surgical specimens consisted of the three teeth and numerous fragments of a cyst. The cuspid's crown was surrounded by a membranous insertion. The cyst was translucent, and its generally smooth inner surface showed scattered gray nodules measuring 0.01 to 0.55 cm. Histologically the cyst and its nodular outpouchings were lined by five to six layers of nonkeratinizing squamous epithelial cells covering an edematous stroma (Fig. 2 ) . The epithelium contained tiny brown granulations,...