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Anatomic/radiologic classification of renal cortical nodules.

A cortical nodule is defined as a focus of more normal renal cortical tissue than usual in an otherwise normal kidney. Such nodules can mimic renal tumors on excretory urography. The urographic features of 29 cases of renal cortical nodules were correlated with arteriographic features to determine if a pattern of different anatomic types could be discerned. The cortical nodules fell into three anatomic groups (similar to Hodson's dissection classification): (1) subcapsular, (2) hilar lip, and (3) septa of Bertin. These anatomic groupings are proposed as a classification scheme for radiologic use. Using this classification, it was found that cortical nodules have urographic features that permit distinction of one type of cortical nodule from another. A better understanding of cortical nodules, based on this classification, should result in more certain urographic diagnosis of cortical nodule. Similarly, mistaking a cortical nodule for renal tumor on urography should be less likely to occur.

Adolescent↗

Regenerating nodules of liver cirrhosis: MR imaging with pathologic correlation.

To determine the pathologic basis for low-intensity nodules seen on MR images of the liver in patients with cirrhosis, we obtained spin-echo and gradient-echo MR images in 20 cirrhotic patients in whom partial hepatectomies were subsequently performed for hepatocellular carcinoma. Low-intensity liver nodules were shown on gradient-echo and spin-echo images in eight patients. Pathologic study of the liver in these patients showed that these nodules were regenerating nodules containing hemosiderin. Low-intensity nodules were seen only on T2-weighted spin-echo images in four other patients. Microscopic examination of the liver in these patients showed regenerating nodules without hemosiderin deposits. Broad fibrous septa containing vascular spaces were present in two of these four patients. These results suggest that regenerating nodules containing hemosiderin or those that are surrounded by vascular fibrous septa are visible on MR images as low-intensity nodules and that gradient-echo images are useful in demonstrating nodules with hemosiderin.

Aged↗

Rathke cleft cyst intracystic nodule: a characteristic magnetic resonance imaging finding.

OBJECT: The fluid content of Rathke cleft cysts (RCCs) displays variable appearances on magnetic resonance (MR) images and can appear indistinguishable from other intrasellar or suprasellar cystic lesions. Intracystic nodules associated with individual RCCs have been noted, but to date their significance has not been fully explored. METHODS: The authors retrospectively reviewed MR imaging studies obtained in patients harboring intrasellar or suprasellar lesions that were consistent with RCCs to identify the presence and imaging characteristics of intracystic nodules. An intracystic nodule was present in nine (45%) of 20 patients with an RCC. All intracystic nodules were clearly visible and displayed a characteristic low signal intensity on T2-weighted MR images. The nodule was only visualized on T1-weighted images in four cases, in which it exhibited a consistent high signal intensity similar to that of the cyst fluid. The nodules did not enhance following the intravenous administration of a contrast agent. CONCLUSIONS: Although it is difficult to differentiate RCCs from other sellar cystic lesions because of the variable signal intensities displayed on MR images, the intensity of the intracystic nodule seems consistent on T1- and T2-weighted images, and the nodule is always clearly visible on T2-weighted images. With a nonenhancing cystic lesion that does not cause significant symptoms in the patient, the identification of an intracystic nodule with a characteristic signal intensity will aid in the diagnosis of RCC and the selection of conservative management.

Adult↗

A case of hypervascular hyperplastic nodules in a patient with alcoholic liver cirrhosis.

Most hypervascular nodules in a cirrhotic liver are hepatocellular carcinomas (HCCs); however, some are benign hypervascular hyperplastic nodules. We report a case of benign hypervascular hyperplastic nodules in a 41-year-old male patient without hepatitis B or C virus infection, with a history of alcohol abuse, and diagnosed with an aortic aneurysm. The dynamic computerized tomography of the liver demonstrated multiple nodular lesions on both liver lobes with arterial enhancement and delayed washout. The hepatic angiography showed multiple faint nodular staining of both lobes in the early arterial phase. Magnetic resonance imaging revealed numerous nodules showing high signals on T1 weighted images, with some nodules showing a low central signal portion. The clinical impression was HCC. The ultrasonography-guided liver biopsy, which was performed on the largest nodule (2.5 cm in size), revealed hepatocellular nodules with slightly increased cellularity, unpaired arteries, increased sinusoidal capillarization, and focal iron deposition. However, both cellular and cytological atypia were unremarkable. Although the clinical impression was HCC, the pathological diagnosis was hypervascular hyperplastic nodules in alcoholic cirrhosis. Differential diagnosis of hypervascular nodules in cirrhosis and HCC is difficult with imaging studies; thus, histological confirmation is mandatory.

Adult↗

Differentiation between malignant and benign nodules in the liver: use of contrast C3-MODE technology.

AIM: To investigate the value of contrast-enhanced C3-MODE technology in differentiating malignant nodules of liver from the benign ones. METHODS: Forty-six nodules in 36 patients (29 men and 7 women) were studied by contrast-enhanced C3-MODE technology and contrast-enhanced CT in 1 wk before the biopsy or operation. A low MI monitor and a high MI flash imaging were intermittently performed. After the injection of contrast agent, the period from 10 to 30 s and the time later than 100 s were respectively defined as early arterial phase and the late phase. The vascularities of the liver nodules in the two phases were combined for differential diagnosis. Corresponding to the pathological diagnosis, the accuracy, sensitivity and specificity of contrast-enhanced C3-MODE technology were compared to those of contrast-enhanced CT. RESULTS: By C3-MODE technology, 33 of the 46 liver nodules were demonstrated as defected area in the late phase and were diagnosed as malignant tumors. Of them, 28 with hypervascularity in the early arterial phase were assessed as hepatocellular carcinoma, the other five nodules with rim-like enhancement in the early arterial phase were diagnosed as metastatic tumors. Thirteen nodules were shown as iso or hypervascularity in the late phase as well as centripetal filling in the early arterial phase and we made a diagnosis of hemangioma. Corresponding to the pathological results, the sensitivity, specificity and accuracy of contrast-enhanced C3-MODE technology in differentiating malignant and benign nodules in the liver were 97.0%, 92.3% and 95.7%, respectively. With comparison to those of contrast CT (sensitivity, 94.1%; specificity, 91.7%; accuracy, 93.5%), the difference was not significant. CONCLUSION: Contrast-enhanced C3-MODE technology can effectively differentiate malignant liver tumors from the benign nodules. It highly agrees diagnostically with the pathology. We suggest that it provides a new approach for differential diagnosis of liver nodules in addition to contrast-enhanced CT.

Adenocarcinoma↗

Early formation of the nodule in Guatemalan onchocerciasis.

Thirty-eight nodules containing adults of Onchocerca volvulus were removed from 36 patients who had no detectable microfilariae in skin snips. Worms were digested from nodules in collagenase solution, maintained alive in vitro, and the number, sex, and state of fecundity were recorded. A total of 48 female and 8 male worms were recovered; 39 females were in the nodules without the presence of a male. Eleven females (22.9%) had microfilariae in utero or produced microfilariae in vitro; seven of these were found together with males in the nodules while four were not. No nodules were found around male worms unless a female was also present. These observations indicate that the nodule forms only around female worms and that mating probably occurs before or early during nodule formation. Furthermore, the production of microfilariae by the the female is not essential for nodule formation since many nodules contained non-fecund, living females.

Animals↗

Effect of salt stress on nodulation and nitrogen fixation in legumes.

It is now well established that almost all phases of root nodule development in legumes are adversely affected by saline conditions in the rooting medium. There is also a general agreement that the rhizobia are more tolerant to salt stress than the host plant, but they show considerable strain variability in growth and survival under saline conditions. Inhibitory effect of salinity on nodulation has been attributed to decrease in rhizobial colonisation and shrinkage and lack of root hair formation. Salt stress also induces premature senescence of already formed nodules. Both N2-fixation activity and nodule respiration are inhibited sharply on exposure of plants to saline conditions. The decrease in N2-fixation has been ascribed to direct effect on nitrogenase activity or an indirect effect through decrease in leghemoglobin content, respiratory rate, malate concentrations in nodules and photosynthate availability. Salinity increases oxygen diffusion resistance in the nodules and alters their ultrastructure. Decrease in N2-fixation in nodules under salinity is also accompanied by parallel decrease in the activity of H2O2-scavenging enzymes like catalase, ascorbate peroxidase and the level of antioxidants like ascorbic acid. Nodules appear to undergo osmoregulation under saline conditions by accumulating physiologically compatible solutes like proline, sugars (pinnitol) and lactic acid. The intensity of the adverse effects of salinity on nodule functioning depends on plant species, rhizobial strain, duration of exposure to saline conditions, nature, concentration and mode of salt application.

Fabaceae↗

Cytology and cytogenesis of neoplastic (hyperplastic) hepatic nodules.

Cytochemical and electron microscopic investigations of neoplastic nodules induced in the rat liver by nitrosomorpholine or thioacetamide show that most neoplastic nodules are comprised of a rather heterogeneous cell population. At least four different types of altered hepatocytes can be distinguished: (a) "clear" glycogen storage cells with a dislocation and relative reduction of the granular endoplasmic reticulum; (b) "acidophilic" glycogen storage cells with a hypertrophy of the agranular endoplasmic reticulum; (c) fat-storing cells; and (d) basophilic cells poor in glycogen and rich in ribosomes. In addition, there are diverse intermediate cell types. The cytochemically demonstrable activity of glucose-6-phosphatase is reduced in most neoplastic nodules, but it may also be normal or even increased. The clear and the acidophilic cells precede the development of the neoplastic nodules by weeks and months. They usually form foci which are taken to be preneoplastic lesions. During the formation of neoplastic nodules and hepatocellular carcinomas originating for such foci the glycogen of the clear and the acidophilic cells is progressively reduced, whereas the number of ribosomes (basophilia) increases. This process, which may be accompanied by a transitory accumulation of fat, leads to the evolution of basophilic carcinoma cells. We conclude from these observations that the majority of the neoplastic nodules consist of a mixture of precancerous, definitely cancerous, and diverse intermediate cells. Neoplastic nodules in which basophilic cells prevail may already be carcinomas. Although the neoplastic nodules seem to be a frequent precursor of hepatocellular carcinomas, the latter may also develop without going through the nodule stage.

Animals↗

Perlecan-stimulated nodules undergo chondrogenic maturation in response to rhBMP-2 treatment in vitro.

The heparan sulfate proteoglycan, perlecan, is localized to hypertrophic chondrocytes in the growth plates of long bones. Mice mutants for perlecan display severe cartilage and skeletal defects. Previously, we demonstrated that C3H10T1/2 fibroblasts cultured on perlecan stimulated extensive formation of dense nodules reminiscent of embryonic cartilaginous condensations. These nodules stain intensely with Alcian blue, and antibodies specific for collagen type II and aggrecan; however, nodules do not express collagen type X, a marker of chondrogenic maturation. In this investigation, we tested the hypothesis that addition of rhBMP-2 to perlecan-induced nodules would promote chondrogenic maturation in vitro. C3H10T1/2 fibroblasts were seeded in Lab-Tek chambered "Permanox" slides uncoated or coated with perlecan (B&D, 5 microg/well), at a density of 2 x 10(5) cells/well. The cells were maintained in CMRL-1066 media supplemented with ascorbic acid, citrate, and pyruvate (50 ng/ml). C3H10T1/2 fibroblasts seeded on perlecan-coated wells began to condense and form cell aggregates within 15 min. On the third day postplating, the media was replaced and supplemented with or without rhBMP-2 (50 ng/ml, Genetics Institute). On day 6 of culture, microscopy revealed that rhBMP-2-treated cultures had significantly proliferated; however, untreated cultures had not. By day 12 of culture, confocal microscopy revealed that perlecan-stimulated nodules treated with rhBMP-2 express a late stage marker of chondrogenesis (collagen type X). Morphologically, cells expressing collagen type X in rhBMP-2-treated nodules appear larger in diameter, relative to cells not expressing collagen type X. Cells cultured on plastic and treated with rhBMP-2 did not form nodules, but attached and spread, yielding a high-density monolayer. In response to rhBMP-2 treatment, these cells also express collagen type X. However, the appearance of collagen type X occurs at a later time point relative to the appearance of collagen type X in perlecan-stimulated nodules. Thus, perlecan-stimulated nodules do mature at a faster rate when treated with rhBMP-2 relative to monolayer cells.

Animals↗

[X-chromosome inactivation patterns of different tumor nodules in multiple leiomyomas of uterus].

OBJECTIVE: To describe the relationship among different tumor nodules in multiple leiomyomas of uterus. METHODS: Genomic DNA was extracted from fresh tissue samples, digested through incubation with methylation-sensitive Hha I or Hpa II, and amplified via PCR for androgen receptor (AR) and phosphoglycerate kinase (PGK) genes. The length polymorphism on AR gene was demonstrated by denaturing polyacrylamide gel electrophoresis and silver staining, the PGK gene products were treated with Bst XI and resolved on agarose gels. RESULTS: 112 cases of leiomyomas and one case of leiomyosarcoma were examined, 89% showing the length polymorphism for AR gene and 30% carrying the polymorphic Bst XI site at PGK locus. Loss of X-chromosome inactivation mosaicism was observed in all the 321 tumor nodules examined from 77 cases, reflecting their clonal cellular composition. The relationship between different nodules was evaluated by their X-chromosome inactivation patterns in the 295 tumor nodules taken from 57 multiple leiomyomas. Similar inactivated alleles were found in all nodules in 30, in most nodules in 7 cases, similar to a multi-nodular leiomyosarcoma, while 20 cases showed near-random distribution of the inactivated alleles in different nodules, indicating their multicentric origins. No relevance was found between this difference and any histopathological parameters including number of mitotic figures and occurrence of bizarre nuclei and degeneration. In addition, an identical mutation and loss of heterozygosity were found at the AR locus in two apparently discrete tumor nodules in one case, providing further evidence for the unicellular origin of these lesions. CONCLUSIONS: The multi-nodular leiomyomas may be classified into multicentric, unicentric types, as well as a mixed type. It remains to be clarified whether different nodules in the unicentric cases originate from a parent tumor by migration or by spreading.

Base Sequence↗

[Umbilical metastasis: Sister Mary Joseph's nodule].

Sister Mary Joseph (1856-1939), who was superintendent nurse at St. Mary's Hospital in Rochester, Minnesota, U.S.A. (at present Mayo Clinic), observed that patients with intra-abdominal or pelvic malignancy often had an umbilical nodule. In 1949 the English surgeon Hamilton Bailey, in his famous textbook "Demonstrations of Physical Signs in Clinical Surgery", coined the term "Sister Joseph's nodule" for umbilical metastases. To date, more than 400 cases of Sister Mary Joseph's nodule have been described in the literature. The nodule may be painful and ulcerated, sometimes with pus, blood, or serous fluid. It is usually a firm nodule measuring 0.5-2 cm, although some nodules may reach up to 10 cm in size. Tumor may spread to the umbilicus through lymph ducts, blood vessels, contiguous extension, and embryologic remnants. Sister Mary Joseph's nodule can be the first manifestation of an underlying malignancy or an indication of a recurrence in a patient with a previous malignancy. The most common origin of Sister Mary Joseph's nodule in women is ovarian carcinoma and in men--gastric carcinoma. Sister Mary Joseph's nodule has traditionally been considered a sign of advanced primary malignancy with an associated poor prognosis; the average survival time has been reported to be 11 months with < 15% of the patients surviving >2 years. In some patients, however, depending on the state of the primary neoplasm and the patient's general condition, surgery and/or chemotherapy may improve survival.

Abdominal Neoplasms↗

Analysis of DNA adducts in putative premalignant hepatic nodules and nontarget tissues of rats during 2-acetylaminofluorene carcinogenesis.

Exposure of rats to a standard four-cycle feeding regimen of 0.06% 2-acetylaminofluorene (AAF) results in the formation of putatively premalignant hepatic nodules, but the types and magnitude of DNA adducts formed in these nodules has not been previously examined. By using a sensitive 32P-adduct assay (R. C. Gupta, Cancer Res., 45: 5656-5662, 1985), we analyzed the DNA adduct lesions in individual hepatic nodules at various times during and after exposure to AAF. Kidney, spleen, and testis were included as nontarget tissues. No qualitative difference was observed in the DNA adducts found in hepatic nodules and nontarget tissues; however, quantitative differences occurred. At least one unknown and two known (dG-C8-AF and dG-N2-AAF) DNA adducts were detected, with dG-C8-AF being predominantly (96-98%) formed, in all tissues examined. At the end of the first three weeks of AAF feeding, the concentration of the deacetylated adduct dG-C8-AF in liver (223 fmol/micrograms DNA) was found to be about 2, 6, and 5 times higher than in kidney, spleen, and testis, respectively. The concentration of the N2-acetylated adduct in liver (4.5 fmol/micrograms DNA) was 4-fold higher than in kidney and strikingly higher (51- and 42-fold, respectively) than in spleen and testis. At the end of the fourth feeding cycle, total DNA adducts measured in the hepatic nodules ranged from 30-100 fmol/micrograms DNA, while the "surrounding liver," kidney, spleen, and testis showed 235, 218, 62, and 28 fmol adducts/micrograms DNA, respectively. Sixty days following the cessation of AAF, the binding in both the persistent nodules and liver had decreased to 7% of their respective levels measured at the end of the fourth cycle, while adducts in kidney, spleen, and testis were 32%, 18% and 19%. After 88 days, the binding levels in the nontarget tissues declined further, but no additional adduct removal occurred in the nodules. Our data indicate that (a) although the metabolic apparatus for activation of AAF is diminished in the hepatic nodules, a significant level of adduct formation occurs in the cells of this putative, premalignant lesion, and (b) unlike in the nontarget tissues, repair processes in the premalignant nodules may not be operative several weeks after the cessation of AAF exposure.

2-Acetylaminofluorene↗

Progression in hepatocarcinogenesis: differences in growth and behavior of transplants of early and later hepatocyte nodules in the rat spleen.

Hepatocyte nodules were induced in Fischer 344 rats using the resistant hepatocyte model. Nodules harvested at 5, 24, or 25 weeks after initiation were isolated, diced, and transplanted into the spleen of normal rats and observed for periods up to 104 weeks. In the first experiment, 50% of the animals developed hepatocellular carcinoma, some with invasion and metastasis, by 70 to 104 weeks. In the second experiment, transplants of 5-week nodules grew very slowly and diffusely in the spleen, as did normal liver, but retained at least some of their phenotypic properties. In contrast, transplants of 25-week nodules grew into nodules up to 2.5 cm in diameter by 70 weeks. Two of the larger nodules had smaller nodules within resembling trabecular carcinoma. Transplants from the liver surrounding the 25-week nodules did not grow and produced no nodules by 70 weeks after transplantation. The implications of these observations in the study of progression in hepatocarcinogenesis are discussed briefly.

Animals↗

Scanning electron microscopy of rat liver hyperplastic nodules induced by diethylnitrosamine.

Rat liver hyperplastic nodules induced by diethylnitrosamine (DEN) were observed by scanning electron microscopy (SEM). Liver hyperplastic nodules were made according to the methods of Solt and Farber. Hyperplastic nodules appeared 4 weeks after DEN administration and these early hyperplastic nodules continued growing and became eosinophilic hyperplastic nodules 5 to 6 weeks after DEN administration. SEM revealed that hyperplastic nodules were composed of enlarged hepatocytes which formed two-cell-thick plates. Intercellular surfaces of hepatocytes were covered with numerous microvilli. Dilation of bile canaliculi was marked in hyperplastic nodules. Kupffer cells were not seen in the sinusoids. Sinusoidal endothelia had no fenestrae. Transmission electron microscopy revealed the endothelium had a continuous basement membrane. In conclusion, hyperplastic nodule has the intermediate features between liver cirrhotic nodule and liver cell adenoma or hepatocellular carcinoma.

Animals↗

[Diagnostic value of thermography and Tc 99m bleomycin scintigraphy for nodules of the thyroid (author's transl)].

The combined interest of thermography and 99mTc Bleomycin scintigraphy in the differential diagnosis of a cold thyroid nodule was evaluated in 86 patients. In all cases a histological examination was performed. Of the 30 malignant nodules (clinically suspect and solitary nodules) 21 (70%) showed concentrations of 99mTc Bleomycin while only 7 of the 12 solitary malignant nodules did so. Among the 54 benign nodules the false positive rate was 54%. Thermography was positive in 26 (87%) of the 30 malignant nodules and in only 8 (67%) of the 12 solitary malignant nodules. For the 54 benign nodules the false positive rate was 72%. The combined results of the study do not provide any improvement in diagnostic accuracy. Thus it can be said that applications of 99mTc Bleomycin and thermography in the diagnosis of solitary hypofixiant nodules are of limited value.

Bleomycin↗

Endoscopic appearances of colonic lymphoid nodules: new faces of an old histopathological entity.

OBJECTIVES: Colonic lymphoid nodules, also known as focal colonic lymphoid hyperplasia, have been previously described either as an indication of disease or as a normal variant in adults, with current opinion favoring the latter. The finding of isolated or confluent colonic lymphoid nodules on colonoscopy may nevertheless cause confusion with other endoscopic diagnoses. METHODS: In this study, we describe new endoscopic features of colonic lymphoid nodules, and we correlate them with other clinical and histopathological characteristics. Our experience is based on thorough evaluation of 13 cases of colonic lymphoid nodules that were consecutively observed during colonoscopy over the past 2 yr. RESULTS: Colonic lymphoid nodules may appear as red macules, as circumferential target lesions (halo sign), or as raised papules; they occur in both men and women, predominantly affect the rectum, and appear to be of no clinical significance. Histologically, colonic lymphoid nodules may involve the mucosa or the submucosa, in the form of either lymphoid aggregates or lymphatic nodules. CONCLUSIONS: With the widespread use of video colonoscopy, the macular or papular endoscopic characteristics of colonic lymphoid nodules should be increasingly recognized, confirmed histologically, and distinguished from other pathological lesions. Improved endoscopic recognition will allow the potential association of colonic lymphoid nodules with other colonic pathology to be eventually elucidated.

Adult↗

Inhibition of cell proliferation by ciprofibrate in glutathione S-transferase P1-1-positive rat hepatic hyperplastic nodules.

Previous studies have demonstrated that short-term treatment with a peroxisome proliferator (PP) decreased the size and number of genotoxic carcinogen-induced hepatic hyperplastic lesions identified by gamma-glutamyl transpeptidase (GGT) or glutathione S-transferase P1-1 (rGSTP1-1) staining. However, longer-term PP treatment of animals bearing similar hepatic hyperplastic lesions produced an increase in both the size and number of liver tumors. To characterize the hepatic hyperplastic lesions which are inhibited or promoted by PP, a unique double labeling technique was developed to determine the relative rate of cell division (e.g., DNA synthesis) in rGSTP1-1-positive nodules before and after ciprofibrate (Cip) treatment. rGSTP1-1-positive nodules were induced with the Solt-Farber resistance protocol (diethylnitrosamine-2-acetylaminofluorene partial hepatectomy). Eleven weeks after diethylnitrosamine initiation, 3 groups of rats were maintained on a control chow diet or switched to a powdered chow diet containing 0.025% Cip or 0.05% phenobarbital (PB) for the last 8 days of the experiment. A minipump implanted in the abdominal cavity released [methyl-3H]thymidine continuously for 72 h and was then removed prior to CIp or PB treatment. A second minipump was then implanted which released bromodeoxyuridine to the abdominal cavity 5 days after the start of Cip or PB administration and lasted for 72 h until the termination of the experiment. Both the [methyl-3H]thymidine and bromodeoxyuridine labeling indices (LIs) were determined in the same group of cells within individual rGSTP1-1-positive nodules in the right posterior lobes of livers. PB treatment increased both the average number of persistent GGT-positive nodules and the ratio of persistent GGT-positive to rGSTP1-1-positive nodules/cm2. In contrast, Cip treatment greatly decreased the average number and area of persistent GGT-positive nodules, as well as the ratio between persistent GGT-positive and rGSTP1-1-positive nodules/cm2. Cip treatment also resulted in a 40% decrease in the average LI in the rGSTP1-1-positive nodules. In some rGSTP1-1-positive nodules, the LI was decreased from > 40% prior to Cip treatment to < 5% afterward, suggesting that Cip treatment interrupted progression in these nodules. Such drastic changes in the LI before and after treatments were not observed in either PB- or vehicle-treated (control) animals. A number of small nodules with a high bromodeoxyuridine LI but with no or very few [methyl-3H]thymidine-labeled nuclei and negative GGT and rGSTP1-1 staining were detected only in the Cip group.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

The head nodule and ocular onchocerciasis in Africa.

In a population survey in 1970/72 the prevalence of head nodules was found to be 1.7% in 1098 cases of onchocerciasis in the rain-forest and 0.6% in 1128 cases in the Sudan-savanna of Cameroon. In a follow-up survey in the same villages 3-4 years later more attention was given to the detection of head nocules, and the corresponding prevalences were 5.5 and 5.0%. In the follow-up survey a strong associated was demonstrated between the presence of head nodules and lesions of both the anterior and posterior segments of the eye. The relative risks of having eye lesions in patients with head nodules compared with those without were 2.9 and 7.5 in the rain-forest and savanna respectively. In a group of 483 clinic cases with ocular onchocerciasis from the savanna palpable head nodules were detected in 23.6%, and in a further 140 selected cases from the same area with posterior segment eye lesions, head nodules were detected in 31.4%. Confirmation of the onchocercal origin of the nodules was obtained in doubtful cases by biopsy. Many head nodules probably remain undetected in onchocerciasis surveys. They are often very small, flat, and hard, and tightly adherent to the under-lying periosteum, and the patient will often point out the presence of a nodule even when none has been detected after careful examination. The presence of a head nodule has long been one of the recognized "risk factors" associated with a high prevalence of blindness in Central America, but there have been no detailed studied in African onchocerciasis. A trial is in progress to assess the effect of nodulectomy on the development of ocular lesions.

Adolescent↗