LOT and HOT or not. The proliferation of clinically insignificant and poorly characterised types of renal neoplasia.

The classification of malignant tumours is influenced by both immunohistochemical and molecular genetic findings. This is highlighted in the latest World Health Organization classification of renal neoplasia, which has a tumour category of 'tumours that are molecularly defined'. This implies that the defining molecular features are integral to tumourigenesis, which may not necessarily be the case. Renal oncocytoma is recognised as a benign tumour with variable morphology and immunoexpression. A variant of these tumours is hybrid oncocytic chromophobe tumour, which has features of both oncocytoma and chromophobe renal cell carcinoma and may, on rare occasions, show malignant behaviour. Recent reports have proposed two further entities with eosinophilic cytoplasm and varying nuclear pleomorphism, designated low grade oncocytic tumour (LOT) and eosinophilic vacuolated tumour (EVT), formally known as high grade oncocytic tumour (HOT). The diagnosis of these apparently benign tumours was made on the basis of morphological and immunohistochemical features. More recently it has been claimed that the mutations in the mTOR pathway are also a diagnostic feature and it is further suggested that these mutations are key to the pathogenesis of these tumours. As is seen in oncocytoma, immunohistochemical expression of tumours included in series of LOT and EVT is variable. The mutations in the mTOR pathway, where detected, were not constant, with any combination of mTOR, TSC1 and/or TSC2 being involved. A major issue is that in many of the studies full comparative genomic hybridisation results are not presented. In addition it is well recognised that mTOR mutations are seen in a variety of renal tumours. In view of these conflicting results, the rarity of these tumours and their apparent benign nature, raises questions as to why these tumours should be considered specific entities.

Metastatic endometrial endometrioid carcinoma mimicking pilomatrixoma of the distal vagina.

Endometrioid carcinoma with a prominent squamous component has the ability to mimic pilomatrixoma. One previous case is documented of cutaneous metastasis in the upper limb derived from ovarian endometrioid carcinoma mimicking pilomatrixoma. Here, we describe a case of metastasis of endometrial endometrioid carcinoma in the distal vagina, treated with radiotherapy and later resected. The histology of the lesion was thought initially to represent pilomatrixoma; this has not previously been described in the vagina, where no hair matrix cells are normally present. We hypothesise that radiotherapy may have effectively 'sterilised' the glandular component, blinding the malignant features. Further management was significantly altered by the reinterpretation of this result as metastatic disease. We emphasise that in the context of known endometrioid carcinoma, the diagnosis of pilomatrixoma should be made with caution, particularly where radiotherapy has been used.

Proteins from formalin-fixed paraffin-embedded prostate cancer sections that predict the risk of metastatic disease.

BACKGROUND: Prostate cancer is the most frequently diagnosed cancer in men and the third leading cause of cancer related deaths among men living in developed countries. Biomarkers that predict disease outcome at the time of initial diagnosis would substantially aid disease management. RESULTS: Proteins extracted from formalin-fixed paraffin-embedded tissue were identified using nanoflow liquid chromatography-MALDI MS/MS or after separation by one- or two-dimensional electrophoresis. The proteomics data have been deposited to the ProteomeXchange with identifier PXD000963. A list of potential biomarker candidates, based on proposed associations with prostate cancer, was derived from the 320 identified proteins. Candidate biomarkers were then examined by multiplexed Western blotting of archival specimens from men with premetastatic disease and subsequent disease outcome data. Annexin A2 provided the best prediction of risk of metastatic disease (log-rank Chi squared p = 0. 025). A tumor/control tissue >2-fold relative abundance increase predicted early biochemical failure, while <2-fold change predicted late or no biochemical failure. CONCLUSIONS: This study confirms the potential for use of archival FFPE specimens in the search for prognostic biomarkers for prostate cancer and suggests that annexin A2 abundance in diagnostic biopsies is predictive for metastatic potential. Protein profiling each cancer may lead to an overall reduction in mortality from metastatic prostate cancer as well as reduced treatment associated morbidity.

Patterns of failure after iodine-125 seed implantation for prostate cancer.

PURPOSE: To determine the site of relapse when biochemical failure (BF) occurs after iodine-125 seed implantation for prostate cancer. MATERIALS AND METHODS: From 2001-2009, 500 men underwent implantation in Wellington, New Zealand. Men who sustained BF were placed on relapse guidelines that delayed restaging and intervention until the prostate-specific antigen (PSA) was ⩾20 ng/mL. RESULTS: Most implants (86%) had a prostate D90 of ⩾90%, and multivariate analysis showed that this parameter was not a variable that affected the risk of BF. Of 21 BFs that occurred, the site of failure was discovered to be local in one case and distant in nine cases. Restaging failed to identify the site of relapse in two cases. In nine cases the trigger for restaging had not been reached. CONCLUSIONS: If post-implant dosimetry is generally within the optimal range, distant rather than local failure appears to be the main cause of BF. Hormone treatment is therefore the most commonly indicated secondary treatment intervention (STI). Delaying the start of STI prevents the unnecessary treatment of men who undergo PSA 'bounce' and have PSA dynamics initially mimicking those of BF.

A comparison of cancer statistics in New Zealand and Australia: 1996-2007.

AIM: To compare the burden and outcomes of cancer in New Zealand with those in Australia. METHODS: For the years 1996-1997 and 2006-2007, the incidence and mortality of cancer in New Zealand and Australia was compared to determine if differences between the two countries had changed over the decade under study. Summarised cancer data from New Zealand and Australia, age standardised to the 2002 World Health Organisation's standard population, were used to make the comparisons. RESULTS: For the 11 year timeframe of this study, total rates of cancer incidence reduced in New Zealand and increased in Australia. The incidence of cancer in New Zealand, relative to Australia, changed from an excess of +10.3 to a deficit of -27.5 per 100,000 people. When considering the excess in terms of gender, the annual excess of cancer registrations for New Zealand females fell from +19.9 to +0.9 per 100,000, and male cancer registration fell from an excess of +3.7 to a deficit of -58.0 per 100,000, due almost entirely to a surge in prostate cancer registration in Australia. Over the same 11-year timeframe, cancer-specific mortality rates decreased in both countries, but there was no change in the difference between New Zealand and Australian rates, which remained 10% higher in New Zealand. Similar to findings on 1996/7 data, the main cancer sites responsible for the overall excess mortality in 2006/7 were colorectal cancer in both sexes, and lung and breast cancer in females. CONCLUSION: The persisting different cancer mortality rates between the two countries is likely to have been partly due to lifestyle and ethnic differences in the populations, and partly due to New Zealanders presenting with more advanced cancers and having less easy access to some treatments. Until we know the relative contributions of these factors, it will be difficult for New Zealand to plan interventions in the future which have a good chance of lifting our cancer survival rates to those of our closest neighbour. The collection of clinical stage on all new cancer registrations would provide the base information required.

Cathepsin D Expression in Colorectal Cancer: From Proteomic Discovery through Validation Using Western Blotting, Immunohistochemistry, and Tissue Microarrays.

Despite recent advances in surgical techniques and therapeutic treatments, survival from colorectal cancer (CRC) remains disappointing with some 40-50% of newly diagnosed patients ultimately dying of metastatic disease. Current staging by light microscopy alone is not sufficiently predictive of prognosis and would benefit from additional support from biomarkers in order to stratify patients appropriately for adjuvant therapy. We have identified that cathepsin D expression was significantly greater in cells from invasive front (IF) area and liver metastasis (LM) than those from main tumour body (MTB). Cathepsin D expression was subsequently examined by immunohistochemistry in tissue microarrays from 119 patients with CRC. Strong expression in tumour cells at the IF did not correlate significantly with any clinico-pathological parameters examined or patient survival. However, cathepsin D expression in cells from the MTB was highly elevated in late stage CRC and showed significant correlation with subsequent distant metastasis and shorter cancer-specific survival. We also found that macrophages surrounding tumour cells stained strongly for cathepsin D but there was no significant correlation found between cathepsin D in macrophages at IF and MTB of CRC patient with the clinic-pathological parameters examined.

Grading of clear cell renal cell carcinoma should be based on nucleolar prominence.

Fuhrman grading of renal cell carcinoma focuses on features of nuclear size, nuclear shape, and nucleolar prominence. Despite the reported widespread usage of Fuhrman grading in clinical studies, there is debate as to the prognostic significance and reproducibility of its criteria. It has been noted that many pathologists rely on assessment of nucleolar prominence alone when grading renal cell carcinoma; however, the validity of this remains unconfirmed. This study was undertaken to determine the relationship of the 3 morphologic components of the Fuhrman grading system with one another and to determine which, if any of these, can be correlated with outcome for clear cell renal cell carcinoma. One hundred twenty-one organ-confined clear cell renal cell carcinomas were examined in this study. Parameters of nuclear size (area, major axis, perimeter) and nuclear shape (shape factor, nuclear compactness) were assessed by image analysis, whereas nucleolar prominence was assigned (grades 1 to 3) using the criteria of Fuhrman. On the basis of the predominant grade present, there were 17 nucleolar grade 1, 90 nucleolar grade 2, and 14 nucleolar grade 3 tumors. When the high-power field in each tumor with the worst nucleolar grade was assessed, there was 1 nucleolar grade 1, 68 nucleolar grade 2, and 52 nucleolar grade 3 tumors. Predominant and worst nucleolar grade correlated with all measures of nuclear size, but not nuclear shape. Worst nucleolar grade and all parameters of nuclear size were significantly associated with outcome. On multivariate analysis, worst nucleolar grade retained a significant association with survival when modeled with nuclear area. Neither worst nucleolar grade nor major nuclear axis/nuclear perimeter was significantly associated with survival when modeled together. In this study, we have shown that worst nucleolar grade and nuclear size are of prognostic significance for clear cell renal cell carcinoma. We have further shown the association of worst nucleolar grade with outcome to be independent of nuclear area, whereas it is a dependent variable when tested against other parameters of nuclear size. These findings indicate that worst nucleolar grading alone is a valid grading parameter for clear cell renal cell carcinoma.

Parameters of perineural invasion in radical prostatectomy specimens lack prognostic significance.

The prognostic significance of perineural invasion by prostate cancer is debated. We have evaluated the association between biochemical failure and measurements of perineural invasion in radical prostatectomy specimens. Perineural invasion was identified in sections using S-100 protein immunostaining. For nerves showing invasion, the involved nerve closest to the edge of the prostate and to the surgical excision margin, as well as the diameter of these nerves, the largest nerve showing perineural invasion and its proximity to the excision margin, and the percentage of nerves showing perineural invasion up to 1.75 mm from the excision margin was determined and tested against time to prostate-specific antigen failure, along with preoperative prostate-specific antigen levels, highest Gleason primary grade, Gleason score and TNM T category. Perineural invasion was present in 90% of cases, with extraprostatic perineural invasion in 25% of tumors. Diameter of nerves showing perineural invasion ranged from 11 to 680 microm and the shortest distance to the surgical excision margin ranged from 33 to 2.57 mm. Perineural invasion density ranged from 6 to 96%. Gleason scores were six in 58 cases, seven in 43 cases, eight in three cases and nine in one case. Clinical T categories were T1c in 75 cases, T2a in 22 cases, T2b in five cases, T2c in two cases, T3 in one case. During a follow-up period of 11 to 55 months (median 26 months), 27 patients showed prostate-specific antigen failure. On univariate analysis only presence of extraprostatic perineural invasion, among parameters of perineural invasion, showed a weak correlation with outcome, while on multivariate analysis this lost significance and preoperative prostate-specific antigen levels, Gleason score and excision margin status were independently associated with biochemical failure. We conclude that the investigated parameters of perineural invasion do not predict prostate-specific antigen recurrence in radical prostatectomy specimens.

Cyst fluid cytology of cerebellar hemangioblastoma: a case report.

Hemangioblastoma, an uncommon central nervous system neoplasm, commonly located in the cerebellum and more rarely in the spinal cord. In this report, we described the cytologic features of a cerebellar hemangioblastoma in a 53-year-old man, present in cystic fluid obtained at cranioctomy. Cytologic preparations were characterized by well preserved, scattered dissociate, and occasional groups of stromal cells with round to oval nuclei, fine chromatin, and lacelike or granular, vacuolated eosinophilic cytoplasm with a foamy appearances. In addition, calcific material, endothelial-like cells, blood, and macrophages were seen. The radiologic impression, cytologic features, and location led us to suggest the possibility of hemangioblastoma. Subsequent histopathological material revealed the characteristic features of hemangioblastoma.

Prostate cancer--are ethnic minorities disadvantaged?

BACKGROUND: This study, investigating ethnic differences in the diagnosis and treatment of prostate cancer, was performed because of a perceived paucity of Maori men receiving treatment for localised prostate cancer in the greater Wellington region. It was considered that if real differences could be demonstrated between Maori and non-Maori, it would raise questions as to whether cancer services were equally accessible to all sections of the population, one of the main objectives of the New Zealand Cancer Control Strategy. PATIENTS AND METHODS: The database for this study includes men from the greater Wellington region, presenting with clinically localised prostate cancer between 1996 and 2007, who were treated using three defined protocols. There were 271 men with low-risk prostate cancer treated with brachytherapy (permanent iodine seed implantation), and 188 men with intermediate- or high-risk prostate cancer who were entered into sequential clinical trials run by the Trans-Tasman Radiology Oncology Group (96.01 and RADAR 03.04) and treated with radical external beam radiotherapy. Each man on the database was allocated to a major ethnic group based on ethnic categories defined in the 2006 New Zealand Census. Comparisons were then made of the observed ethnic mix of men in the low- and intermediate/high-risk groups with the expected percentages derived from Census and Cancer Registry data. RESULTS: Ten Maori men were on the database, compared to 44 expected, and one Pacific man, compared to 37 expected. The same pattern of under-representation of these ethnic minorities was seen for both low-risk and intermediate/high-risk localised prostate cancer. CONCLUSION: As Cancer Registry data indicate that Maori have a lower incidence of prostate cancer compared to non-Maori, but a higher mortality rate and ratio (deaths/registrations), it is probable that during the period covered by this study, Maori were more likely to present with advanced cancer no longer confined to the prostate. The most likely explanation for this is that Maori have a cultural reluctance to present for health care until forced to by disabling symptoms. Longstanding negative messages from government agencies on the value of prostate cancer screening have done little to encourage the attitudinal change necessary for earlier, and more beneficial, engagement with health services.

Outcome prediction for renal cell carcinoma: evaluation of prognostic factors for tumours divided according to histological subtype.

A wide variety of parameters have been investigated for their prognostic significance in mixed series of renal cell carcinoma (RCC). The classification of RCC into separate types with differing morphology, genotype and probable clinical outcome has led to a re-evaluation of many prognostic parameters with studies confined to a single RCC morphotype. Tumour stage remains the most important predictor of RCC outcome and recent investigations have focused upon tumour diameter and the prognostic significance of stromal, vascular and lymphatic invasion within the renal sinus. In large tumour series, morphotype has been correlated with patient survival, with clear cell RCC being associated with a less favourable outcome than chromophobe RCC and to a lesser extent papillary RCC, for organ confined tumours. The prognostic significance of nuclear grading remains controversial. Fuhrman grading has been shown to have prognostic utility for clear cell RCC in some series. Recent studies have shown that for papillary RCC, grading should be based upon nucleolar size and that Fuhrman grading is inappropriate for chromophobe RCC. Proliferative indices based upon a variety of markers have been correlated with outcome for clear cell RCC (Ki-67, AgNORs, p21(waf1/cip1) and p27(Kip1)) and papillary RCC (Ki-67, AgNORs), although in some series prognostic significance was lost on multivariate analysis. The presence of tumour necrosis has been shown to predict survival for clear cell and chromophobe RCC, and in clear cell RCC quantification of tumour vascular density has been correlated with outcome. Several molecular markers have been investigated for prognostic significance, mostly in clear cell RCC. Although some of these markers have been shown to be significantly associated with survival, these findings remain to be confirmed in large scale follow-up studies.

Fine needle aspiration cytology of unsuspected metastatic hurthle cell carcinoma of the thyroid and its pitfalls: a report of two cases.

We discuss two cases of unsuspected metastatic thyroid carcinoma of Hurthle cell type, presenting as subcutaneous masses in the occipital scalp and supra-acetabular region of the right ilium; clinically suspected to be a lipoma and a vascular tumour, respectively. These two cases were initially investigated by fine-needle aspiration cytology. In case 1, a definitive diagnosis of metastatic Hurthle cell carcinoma was made based on cell block preparation and positive immunohistochemical stains for thyroglobulin and thyroid transcription factor-1. Case 2 was reported as suggesting an oncocytic process, metastatic Hurthle cell lesion. The filter preparations from both cases showed compact sheets and individual large polygonal cells with voluminous granular cytoplasm, eccentric nuclei with minimal atypia and bland chromatin. Scattered haemosiderin-laden macrophages and cystic debris were also identified in both cases. These cases are of interest as the bland cytologic features may lead to an erroneous benign diagnosis. Immunohistochemistry aids the definitive diagnosis of metastatic Hurthle cell carcinoma of thyroid especially when the presence of a previous thyroid lesion is not communicated to the laboratory.

Fuhrman grading is not appropriate for chromophobe renal cell carcinoma.

This study was undertaken to assess the prognostic effectiveness of Fuhrman nuclear grading and the individual components of this grading system, in a series of chromophobe renal cell carcinomas. Eighty-seven cases of chromophobe renal cell carcinoma were investigated. There were 47 males and 40 females, 28 to 78 years of age. The carcinomas ranged from 25 to 180 mm in size and on TNM staging there were 38 stage I, 25 stage II, 22 stage III, and 2 stage IV tumors. Whole tumor Fuhrman grading was grade 1, 6 cases; grade 2, 72 cases; grade 3, 8 cases; and grade 4, 1 case, whereas focal (single high power field) grading was grade 1, 1 case; grade 2, 62 cases; grade 3, 21 cases; and grade 4, 3 cases. On assignment of nucleolar grading using Fuhrman criteria there were 37 grade 1, 44 grade 2, and 4 grade 3 tumors on whole tumor assessment and 3 grade 1, 63 grade 2, and 21 grade 3 tumors on assessment of the high power field showing the greatest degree of nuclear pleomorphism. Measurements of nuclear size showed nuclear area to range from 26.14 to 100.74 microm2, nuclear perimeter from 19.73 to 39.28 microm, and nuclear major axis from 6.49 to 13.21 microm, whereas the ranges of measures of nuclear shape were; shape factor 0.798 to 0.890, compactness 14.260 to 15.843, and feret diameter 5.694 to 11.242. Follow-up ranged from 1 to 150 months and 8 patients died of tumor-related causes 5 to 53 months from diagnosis. On log rank testing against survival, only patient age (P=0.016) and tumor maximum diameter (P=0.0055) were significant, whereas patient sex and TNM stage were not significant. Whole tumor and focal Fuhrman grading, as well as all measures of nucleolar prominence, nuclear size, and nuclear shape showed no significant association with outcome. It is concluded that neither Fuhrman grading, nor any of the components of the Fuhrman grading system, is useful as prognostic indicators for this tumor type.

The evolution of collagen expression in sarcomatoid renal cell carcinoma.

The development of a sarcomatoid morphotype is recognized as an extreme form of dedifferentiation in renal cell carcinoma and is associated with a poor prognosis. Although sarcomatoid renal cell carcinoma shows pronounced spindle cell morphology, clear cell renal cell carcinoma may show early spindle cell change with cellular elongation, and the prognostic significance of this is debated. To determine the relationship between sarcomatoid renal cell carcinoma and clear cell renal cell carcinoma showing early spindle cell change, we have investigated collagen expression using immunohistochemistry in these 2 tumor types. Both sarcomatoid renal cell carcinoma and early spindle cell change tumors showed pericellular interstitial expression of collagen types I and III, whereas sarcomatoid renal cell carcinoma also showed cytoplasmic expression of these collagen types. Expression of these collagen types in typical clear cell renal cell carcinoma was, in occasional cases, limited to faint and patchy staining in a pericellular interstitial distribution. Tumor cells did not stain for collagen type IV in sarcomatoid renal cell carcinoma, early spindle cell change, or typical clear cell renal cell carcinoma. In sarcomatoid renal cell carcinoma, there was diffuse pericellular expression of collagen type V and patchy pericellular expression of collagen type VI, whereas early spindle cell change tumors showed patchy pericellular staining with antibodies to collagen type V. Collagen type VI expression in early spindle cell change was largely confined to the vascular adventitia and areas of scarring, although very occasional foci of faint interstitial staining were also seen. In typical clear cell renal cell carcinoma, staining of collagen types V and VI was limited to the vascular adventitia and foci of desmoplasia, whereas no staining of tumor cell cytoplasm were seen. This study has shown that collagen expression of sarcomatoid renal cell carcinoma differs from that of early spindle cell change and provides validating evidence that these 2 morphotypes should not be considered together for classification purposes.

Karyomegalic interstitial nephritis: a pitfall in urine cytology.

A case of a 44-yr-old Maori female presenting with chronic renal failure due to karyomegalic interstitial nephritis is reported. To our knowledge, this is the first instance this disorder has been reported in a New Zealand Maori. Karyomegalic interstitial nephritis is a rare cause of progressive renal failure, which may be familial, and is frequently associated with a history of recurrent respiratory infections. The urine in this case contained large, pleomorphic cells, mimicking carcinoma. The case therefore illustrates a rare cause of chronic renal failure, and presents an important diagnostic pitfall in the practice of urine cytopathology.

Nucleolar grade but not Fuhrman grade is applicable to papillary renal cell carcinoma.

This study was undertaken to determine the validity of Fuhrman grading in a series of papillary renal cell carcinomas (PRCCs), to examine the interrelationship and prognostic significance of the individual components of the grading system, and further to determine whether any observed predictive value was independent of other prognostic indicators. Ninety cases of PRCC were studied. Fifty-nine tumors were of type 1 and 31 were of type 2. There were 33 TNM stage 1, 26 stage 2, 18 stage 3, and 12 stage 4 tumors, whereas division of cases according to pT category showed 14 pT1a, 20 pT1b, 25 pT2, 15 pT3a, 4 pT3b, and 11 pT4 tumors. Ten tumors were grade 1, 58 grade 2, and 22 grade 3 when predominant Fuhrman grade was assigned, whereas grading according to the high-power field containing the highest grade (focal grade) showed 40 grade 2, 49 grade 3, and 1 grade 4 tumors. Measurements of nuclear size (area, major axis, perimeter) and shape (shape factor, compactness) were undertaken using image analysis. Nuclear area ranged from 27.63 to 116.39 microM, major axis length 6.70 to 14.06 microM, and nuclear perimeter 20.05 to 41.77 microM. Shape factor ranged from 0.805 to 0.878 and compactness from 14.33 to 15.66. Predominant nucleolar grade using the criteria of the Fuhrman classification was nucleolar grade 1 for 13 tumors, nucleolar grade 2 for 56 tumors, and nucleolar grade 3 for 21 tumors. Focal nucleolar grade based on the high-power field showing the greatest degree of nuclear pleomorphism, was grade 2 for 38 tumors and grade 3 for 52 tumors. pT category, TNM stage, focal Fuhrman grade, and PRCC type were significantly associated with survival. Of the various measures of the components of the Fuhrman classification, only focal nucleolar grade was associated with survival, on univariate analysis. On multivariate analysis, focal nucleolar grade and tumor diameter were independently associated with survival, whereas TNM stage retained significance independent of other parameters. It is concluded that assessment of nucleolar prominence rather than Fuhrman grade is applicable for stratification of tumors within TNM stage or pT category for PRCC and that this should be based upon the high-power field showing the greatest degree of nuclear pleomorphism.

Activation of the mucosal immune system in irritable bowel syndrome.

BACKGROUND & AIMS: A role for the mucosal immune system in the pathogenesis of irritable bowel syndrome is suggested by its association with intestinal infections. METHODS: To investigate this, we performed histologic and immunohistologic studies on colonoscopic biopsy specimens from 77 patients with symptoms satisfying the Rome criteria and 28 asymptomatic control patients. RESULTS: Histologic assessment of biopsy specimens from symptomatic patients indicated 3 different groups. The first (38 of 77) had normal conventional histology; however, immunohistology showed increased intraepithelial lymphocytes (median, 1.8-fold; range, 1.74-1.86), lamina propria CD3(+) cells (2-fold; range, 1.55-2.91), and CD25(+) cells (6.5-fold; range, 4.98-8.13) compared with asymptomatic controls. The second group (31 of 77) had nonspecific microscopic inflammation and on immunohistology showed similar increases in lymphocyte populations (not significant vs. the uninflamed group) as well as increased numbers of neutrophil leukocytes and mast cells (P < 0.0001 vs. controls and the uninflamed group). The third group (8 of 77) fulfilled histologic and immunohistologic criteria for classic lymphocytic colitis. CONCLUSIONS: Examination of colonoscopic biopsy specimens from patients meeting the Rome criteria for a clinical diagnosis of irritable bowel syndrome showed subgroups with normal and abnormal conventional histology. All groups showed increased numbers of activated immunocompetent cells in the intestinal mucosa on quantitative immunohistology, implicating the mucosal immune system in pathogenesis.