Melanoses of the gastrointestinal tract

Esophageal Melanocytosis

Esophageal melanocytosis is a rare entity defined by the proliferation of a melanocytic basal layer of the esophageal squamous lining and deposition of melanin in the esophageal mucosa. Esophageal melanocytosis is considered a benign entity of unknown etiology; however, it has been reported as a melanoma precursor. We report a case of esophageal melanocytosis in a diabetic and hypertensive 67-year-old male with recurrent dizziness and syncope for the past 6 months. Given his complaint of dyspepsia, he underwent an upper gastrointestinal endoscopy, in which an esophageal biopsy revealed the diagnosis of esophageal melanocytosis. The definitive diagnosis of esophageal melanocytosis can only be made by histological analysis. The histologic differential diagnoses include melanocytic nevi and malignant melanoma. Therefore, they need to be ruled out.

An Unusual Case of Primary Gastric Balloon Cell Melanoma

Most cases of melanoma found in the gastrointestinal tract are the result of metastasis. Although uncommon and only described in isolated case reports, primary gastric melanoma should be considered when patients present with vague gastrointestinal symptoms and a mass is identified on esophagogastroduodenoscopy or imaging. We describe a case of primary gastric balloon cell melanoma in a 73-year-old man who presented with melena. Given the high morbidity and mortality of gastric mucosal melanoma, early diagnosis and initiation of treatment can lead to improved outcomes and survival.

Melanosis coli: a case report

Background

Melanosis coli is a benign condition characterized by deposition of lipofuscin in colonic mucosa due to long-term laxative use.

Case presentation

Here I am reporting a case of an 85-year-old man who presented with constipation, with a history of long-term herbal medication intake as laxatives, and upon evaluation, he was found to have melanosis coli.

Conclusion

Melanosis coli is a common adverse effect of chronic laxative use which is more common in elderly population with constipation.

Acorn-related acquired pseudomelanosis in Calabrian black pigs

Background

Melanosis of lymph nodes in black pigs has generally been related to regression of congenital melanoma and, occasionally, to ingestion of acorns. The aim of this manuscript is to confirm the hypothesis of a possible acquired acorn-related pseudomelanosis in the Nero Calabrese pig, a swine breed belonging to the group of Italian native breeds and whose coverage area corresponds to the region of Calabria, southern Italy. This pig is characterized by slow-growing subjects, producing, however, high quality meat suitable for the production of sausages and fine hams. The study was carried out on 142 normally slaughtered pigs. All organs were examined. Lymph nodes and intestine (jejunum) were sampled. Histochemistry was performed on deparaffinized histological sections to identify the cell types involved and to characterize the pigment stored. To further confirm the pigmentation disorder, immunohistochemistry was carried out. Total phenolic substances were identified in acorns through the use of a biochemical reaction.

Results

Lymph node pigmentation appears directly related to acorn ingestion, with a higher incidence in the group which was 70% natural fed (acorn of Quercus virgiliana). Moreover, findings obtained revealed how different amounts of phenolic substrates present in Q. virgiliana and Q. ilex acorns can influence the incidence of such exogenous pigmentation.

Conclusion

The findings obtained in this study confirm the acquired nature of the melanin-like pigmentation detected in lymph nodes from acorn-fed swine. Acquired pigmentation must be differentiated from true melanosis as well as from melanosis related to tumor regression of congenital melanoma. This thesaurismosis can be proposed as a marker of wellbeing and quality, confirming that the pigs have been bred and fed in natural conditions.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1934-5) contains supplementary material, which is available to authorized users.

Melanosis Coli: A Helpful Contrast Effect or a Harmful Pigmentation?

Background

Melanosis coli, a brown discoloration of colonic mucosa, is considered as a benign condition mainly observed in patients under chronic anthranoid laxatives. Recent data link this condition with an increased adenoma detection rate. Moreover, its tumorigenic potential and possible association with the development of colorectal cancer remains uncertain. We conducted this study to compare the polyp detection rate and colorectal cancer diagnosis in patients with melanosis against matched control group without melanosis.

Patients and methods

A retrospective single-center study. Patients diagnosed with melanosis coli on colonoscopy over a 15-year period were included. Each melanosis coli patient was matched with three controls by age, gender, setting (inpatient/outpatient), and procedure's indication. Polyp detection rate and diagnosis of colorectal cancer were recorded and compared between the groups before and after adjustment for bowel preparation.

Results

A cohort of 718 patients with melanosis and 2154 controls were included. The polyp detection rates were 33.4% and 21.8% of melanosis and control groups, respectively (P < .001). Melanosis coli, however, was associated with less diagnosis of colorectal cancer than controls (0.3% vs 3.9%; P < .001). In multivariate analysis, melanosis diagnosis on endoscopy was significantly associated with higher polyp detection rate (odds ratio [OR] = 1.986, 95% confidence interval [CI]: 1.626-2.425; P value < .01).

Conclusions

Melanosis coli is not associated with increased diagnosis of colorectal cancer. It is associated, however, with enhanced polyp detection likely due to chromo-endoscopy-like effect.

Adenoma Detection is Increased in the Setting of Melanosis Coli

GOALS

To compare the adenoma detection rate (ADR) during colonoscopy in patients with melanosis coli against matched controls without melanosis.

BACKGROUND

Melanosis coli is a colonoscopic finding in which the colon wall appears darkly pigmented, most often due to extended laxative use, and is considered benign. The pigmentation spares adenomas, which should therefore be more readily detectable in melanosis coli.

STUDY

We identified all patients with melanosis on colonoscopy at our institution over a 5-year period. We matched each patient with 2 controls by age, gender, and endoscopist. We compared the prevalence of adenomas between groups, and used multivariable analysis, adjusting for procedure indication and bowel preparation quality, to determine the independent association of melanosis with adenoma detection.

RESULTS

At least 1 adenoma was detected in 34.7% of melanosis patients and 26.5% of controls [odds ratio (OR)=1.52; 95% confidence interval (CI), 1.04-2.24; P=0.03]. On multivariable analysis, the presence of melanosis remained associated with increased adenoma detection (OR=1.56; 95% CI, 1.05-2.33; P=0.03). Melanosis patients were more likely to have an adenoma ≤5 mm (OR=1.62; 95% CI, 1.04-2.51; P=0.03), but not adenomas 6 to 9 mm or ≥10 mm.

CONCLUSIONS

Melanosis coli is associated with a significant increase in ADR during colonoscopy compared with controls. The increased visibility of adenomas given their contrast with the pigmented background is a likely explanation. Future efforts to identify bowel preparation agents that can induce a similar effect could improve ADRs during colonoscopy.

Melanosis coli in patients with colon cancer

INTRODUCTION

Melanosis coli is a benign lesion affecting the mucosa of the large intestine. There is a relationship between the presence of melanosis and anthraquinone laxative use. Melanosis coli is also observed in patients with colon cancer, but there is doubt whether these two conditions are related.

AIM

To analyze the correlation between melanosis and colon cancer.

MATERIAL AND METHODS

We analyzed retrospectively 436 patients undergoing colon cancer surgery. There were 246 women and 190 men. Patients were divided into three age groups: under 50 years, between 51 and 65 years, and over 66 years. We analyzed sections of the cancer and intestinal mucosa from the tumor's proximal (2-5 cm) and distal (8-10 cm) zone.

RESULTS

Melanosis coli was present in 52 patients, which represents 11.9% of patients with colon cancer. More often it was present in women. The most common location of melanosis and colon cancer was the terminal part of the large intestine. In patients below 50 years of age in both sexes melanosis coli did not occur. In men, melanosis was more common in the age group over 66 years. Intensity of pigmentation was higher in the tumor's distal zone.

CONCLUSIONS

The incidence of melanosis coli increases with age, similar to that of colon cancer. Melanosis was not present inside tumors, in almost half of the cases it was not present in the proximal zone, and the degree of pigmentation increased in distal zone. The cause-effect relationship between melanosis coli and colon cancer remains uncertain.

Primary gastric melanoma: case report of a rare malignancy

We report the case of a 64-year-old white male who presented to his primary care physician with complaints of fatigue. Physical exam was unremarkable and laboratory studies revealed profound anemia, for which the patient received a transfusion. Esophagogastroduodenoscopy revealed a bleeding mass in the proximal stomach that was histologically determined to be malignant melanoma, with immunohistochemical staining demonstrating positivity for SOX10, S100, MART-1, and HMG-45. After an extensive dermatological exam no other primary lesion was identified. Whole body positron emission tomography (18-FDG-PET/CT) demonstrated pathologic uptake only in the area of the proximal stomach. For this reason, primary gastric melanoma was suspected in this patient. The patient underwent subtotal gastrectomy with mass excision followed by Roux-en-Y reconstruction. Very few cases of primary gastric melanoma have been reported. We report this case and present diagnostic criteria for primary non-cutaneous melanoma and discuss potential non-surgical therapies.

Pseudomelanosis of stomach, duodenum, and jejunum

Pseudomelanosis is a rare finding during upper gastrointestinal endoscopy, and is most commonly seen in the duodenum. Involvement of other organs in the upper gastrointestinal tract is extremely rare, with only 1 reported case involving the stomach, duodenum, and jejunum. We present a case of a 60-year-old woman with mild anemia and hematemesis, who was found to have characteristic speckled pattern of gray-black pigmentation on endoscopic examination. To the best of our knowledge, this is the second reported case of pseudomelanosis involving the stomach, duodenum, and jejunum.

Evidence of Oxidative Injury in Pigs With Melanosis Coli

Melanosis coli is a dark discoloration of the colon due to accumulation of pigment-laden macrophages in the lamina propria. Three case submissions were received where rectal discoloration was reported at slaughter in pigs from separate production systems and melanosis coli was confirmed microscopically. Tissues from affected and unaffected cohort pigs were evaluated for evidence of oxidative damage using immunohistochemical staining for 3-nitrotyrosine, 4-hyroxynonenol, and malondialdehyde. Affected colons had significantly greater immunolabeling for all 3 target compounds than unaffected colons ( P ≤ .001, all analyses). Hepatic vitamin E levels were low in both affected and unaffected pigs, and there was a trend toward lower values in affected pigs. Given the limited number of slaughter-collected samples available for this investigation, further study is warranted to elucidate the possible association between low vitamin E concentrations and oxidative damage in cases of melanosis coli in pigs.

Duodenal pseudomelanosis (pseudomelanosis duodeni): a rare endoscopic finding

Duodenal pseudomelanosis (or pseudomelanosis duodeni) is a rare benign condition characterized by black-brown speckled pigmentation of the duodenal mucosa. Collections of pigment-laden macrophages are found in the tips of duodenal villi. The pigment is thought to be mostly composed of ferrous sulfide. Histochemichal stains for iron (Perl's prussian blue) or melanin (Masson-Fontana) may be positive, but are usually negative or unpredictable. Duodenal pseudomelanosis occurs predominantly in middle-aged to old adults and more commonly in females. It is associated with chronic renal failure, arterial hypertension, diabetes mellitus and gastrointestinal bleeding. Medications such as ferrous sulfate, hydralazine, propranolol, hydrochlorothiazide and furosemide are thought to play a role as well. We report a case of a 86-year-old female who presented with a history of watery diarrhea and melena. The patient had a history of high blood pressure and ischemic stroke episodes. She was on multiple medication including hidralazine, captopril, hydrochlorthiazide and aspirin. She was dehydrated, her blood pressure was 96 × 60 mmHg and neurologic examination showed complete left hemiplegia with central VII nerve palsy. Laboratory tests showed normal serum electrolytes and renal function. Hemoglobin level was 10.7 g%. An upper endoscopy showed multiple diminutive black spots throughout the distal duodenal bulb and second portion. Histology showed multiple foci of a brown-black granular pigment inside macrophages within the tips of the villi (pseudomelanosis). Stains for iron and melanin were negative. She was treated with omeprazol, parenteral fluid replacement with saline and partial fasting. After complete recovery she was discharged for ambulatory follow up.

Herbal remedies are the main etiologic factor in melanosis coli, a case series study

Melanosis coli is a brown to black discoloration of the colon mucosa usually associated with long-term ingestion of laxatives. However, melanosis coli can be found in patients with no history of laxative use. Regular use of herbal remedies could be the major source of anthranoid laxatives in such patients. We designed a prospective case series study to identify the clinical characteristics and etiology of melanosis coli in affected patients. This study took place in Ankara, Turkey, between 08/2005 and 11/2006. Patients with endoscopic diagnosis of melanosis coli were interviewed for demographical data and use of herbal remedies. A total of 380 colonoscopies were performed during this period. Melanosis coli was diagnosed endoscopically in 12 patients (3.17%), 11 of whom were found to have characteristic pigment-laden macrophages in histopathological examination. Herbal remedies were the main etiological factor in the development of melanosis coli in 10 out of 11 patients. Diffuse involvement was found in 2 patients who had a history of long-term use. In 8 patients, melanosis coli was located in the left side of the colon. Although melanosis coli is a harmless discoloration of colonic mucosa resulting from complementary or alternative medicine, we believe that this association with herbals was overlooked or not inquired in patients. Therefore, it should be emphasized that “natural” or “alternative” is not equal to “safe”.

Melanosis ilei associated with chronic ingestion of oral iron

Melanosis can affect various parts of the gastrointestinal tract. Melanosis of the colon is not uncommon, while melanosis of the ileum is extremely rare. We report a case of melanosis ilei associated with chronic ingestion of oral iron (256 mg of ferrous sulfate once or twice daily for approximately 5 years) in a 32-year-old woman with end-stage renal disease. The findings of a colonoscopy, which was performed as a part of her medical checkup, were normal up to the cecum; however, numerous brownish-black punctuate pigmentations of the ileal mucosa were observed. Microscopic examination revealed hemosiderosis in the lamina propria of the ileal mucosa, particularly at the tips of villi. The diagnosis of melanosis (hemosiderosis) ilei was made based on the endoscopic and histological findings.

Gastrointestinal side effects of prescription medications in the older adult

Gastrointestinal (GI) symptoms resulting from either prescription medications or over-the-counter drugs are frequently encountered in geriatric practice but often mistaken for symptoms of an organic disease leading to multiple diagnostic studies. The morbidity, mortality, and medical costs associated with drug toxicity, even when restricted to the GI tract, are probably underestimated. The consequences of drug toxicity are quite variable and range from a symptom of mild discomfort (eg, drug-induced diarrhea) at one end of the spectrum, to fatal GI hemorrhage or perforation. Better awareness of the possibility of drug-induced GI tract pathology by primary care physicians improves the recognition of these adverse effects, and ultimately, improves patient care. This review focuses on the most common and well-described drug-related side effects of the GI tract.

“Melanosis” in the small and large intestine

Deposition of pigment in the intestinal mucosa is commonly observed by the endoscopist, especially within the colon, and particularly during investigations for constipation. Pigment may also be detected in the small intestine. Although labeled as melanosis, electron microscopy and X-ray analytical methods have provided evidence that this pigment is not melanin at all, but lipofuscin. Often, herbal remedies or anthracene containing laxatives are often historically implicated, and experimental studies in both humans and animal models have also confirmed the intimate relationship with these pharmacological or pseudo-pharmacological remedies. The appearance of melanosis coli during colonoscopy is largely due to pigment granule deposition in macrophages located in the colonic mucosa. The pigment intensity is not uniform, being more intense in the cecum and proximal colon compared to the distal colon. Possibly, this reflects higher luminal concentrations of an offending agent in the proximal compared to distal colon, differential absorption along the length of the colon, or finally, differences in macrophage distribution within the colon. Mucosal lymphoid aggregates normally display a distinct absence of pigment producing a “starry sky” appearance, especially in the rectosigmoid region. Interestingly, some focal, usually sessile, colonic mucosal neoplastic lesions, rather than submucosal lesions, may be better appreciated as pigment deposition may be absent or limited. If detected, removal and further histopathologic analysis of the polyp may be facilitated.

[Drug-induced enterocolitis]

Drug-induced enterocolitis is a frequent but underdiagnosed disease. Gross and microscopic features are often non-specific, except for particular cases. Drug-induced enterocolitis is usually a diagnosis of exclusion. In this article we describe the pathologic features and causes of various cases of drug-induced enterocolitis.

Classification of eosinophilic gastrointestinal diseases

Diagnosis of eosinophilic gastrointestinal diseases is based on morphological evaluation with regard to localization and density of eosinophil infiltration of the mucosa and/or deeper parts of the oesophagus, stomach, and bowel in biopsy or resection specimens. As with eosinophils in any tissue, in the majority of diseases they are probably a sequel of acute inflammation and do not indicate any specific disease. Eosinophil morphology includes intact cells with bilobated nuclei and eosinophil granules in the cytoplasm and extracellular tissue following activation/degranulation. There is no fixed number of eosinophils that can be used as a cut-off criterion to define disease. Associated histopathological features observed in eosinophilic gastrointestinal disease depend on the site of manifestation and primary disease. Eosinophils are typically increased in allergy-associated colitis in adults and allergic proctocolitis in infants, eosinophilic gastroenteritis and eosinophilic oesophagitis. Their presence can also suggest a drug-induced eosinophilia or the presence of a parasitic infection. In general, eosinophils are increased in inflammatory bowel disease (IBD). They are seen in reflux oesophagitis, coeliac disease, and microscopic and infectious colitis. Eosinophils may be a feature of polyarteriitis nodosa and Churg-Strauss syndrome, and can accompany connective-tissue disease as well as malignant lymphomas and adenocarcinomas of gastrointestinal mucosa.

Drug-induced injury in the gastrointestinal tract: clinical and pathologic considerations

Drug toxicity in the gastrointestinal tract is a common and serious medical problem; the number of drugs that can harm the gastrointestinal tract is impressive. The morbidity, mortality, and medical costs associated with drug toxicity, even when restricted to the gastrointestinal tract, are probably underestimated. Drug-induced gastrointestinal tract pathology is very diverse and can mimic many non-drug-related conditions. Drug toxicity, whether direct or indirect, can be restricted to a segment of the gastrointestinal tract or affect the entire gastrointestinal tract. The consequences of drug toxicity are also quite variable and can range from unimportant pathology (e.g. the relatively common and usually benign drug-induced diarrhea) at one end of the spectrum, to fatal gastrointestinal tract hemorrhage or perforation at the other end of the spectrum. Better awareness of the possibility of drug-induced gastrointestinal tract pathology, by both gastroenterologists and pathologists, and better communication between gastroenterologists, pathologists and other specialists will improve the recognition of drug-induced gastrointestinal tract pathology, and, ultimately, improve patient care. This Review focuses on the most common and well-described drug-related clinicopathologic conditions of the gastrointestinal tract. Much discussion is, therefore, dedicated to NSAIDs--the most commonly prescribed drugs and consequently the drugs most commonly associated with gastrointestinal tract toxicity.

Esophageal melanocytosis morphologic features and review of the literature

Endoscopic or macroscopic esophageal melanocytosis is a benign clinicopathologic entity characterized by melanocytic proliferation in esophageal squamous epithelium and melanin deposition in the mucosa. Little is known about the etiology and natural course of this condition, although it has been suggested to be a precursor of primary esophageal melanoma by some authors. Following a search of the bibliographic databases (PubMed and Medline) regarding esophageal melanocytosis and melanosis, thirty-four cases of isolated esophageal melanocytosis (including one unpublished case from us) were found. The histopathologic features of esophageal melanocytosis are reviewed and its differential diagnosis with other pigmented esophageal lesions is discussed.

Melanosis intestini: case report

The term melanosis in the gastrointestinal tract refers to the accumulation of pigment deposits in the mucosa. Melanosis of the colon is not uncommon and has been associated with certain conditions, however melanosis of the small intestine is extremely rare. Herein, we describe a case in which we observed melanosis not only in the colon, but in the terminal ileum as well, associated with the use of anthraceneline laxatives. The clinical significance of this condition is not clear, however Gastroenterologists and Pathologists should be aware of its existence.

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Chromophobe renal cell carcinoma with microcystic and adenomatous arrangement and pigmentation—a diagnostic pitfall. Morphological, immunohistochemical, ultrastructural and molecular genetic report of 20 cases

We present clinical, morphological, immunohistochemical, ultrastructural and molecular genetic features of 20 cases of a peculiar form of chromophobe renal cell carcinoma (CRCC) with morphology differing from that of conventional CRCC. Microscopically, the typical features of the tumors were microcystic arrangement and formation of adenomatous structures. Microcystic areas were composed of smaller eosinophilic and bigger pale cells having cytological appearance typical of conventional CRCC. Cytological features of the adenomatous structures were mostly different from those of conventional CRCC. They had a typical columnar arrangement with nuclei positioned at the base of the glandular structures and a small amount of a deeply eosinophilic cytoplasm often endowed with brush border facing the lumen of the glands. In addition, all the tumors showed a brown pigmentation. The pigmentation was located mostly extracellularly, where it formed pools of heavy deposits. Microscopic calcifications present in all cases formed psammoma bodies or else the calcifications were more extensive and amorphous in shape. Ultrastructurally, the cells showed features characteristic of CRCC: typical cytoplasmic vesicles were 100-700 nm in size and mitochondria had tubulovesicular, lamellar or circular cristae. Some tumor cells contained dark, variously sized electron-dense pigment granules. Neither melanosomes nor membrane-bound neurosecretory granules were seen. Using fluorescence in-situ hybridization probes for chromosomes 1, 2, 6, 10, 13, 17 and 21, the tumors revealed massive loss of tested chromosomes typical for conventional CRCC. Monosomy of chromosomes 1, 2, 6, 10, 13 and 21 was found in 100, 36, 91, 82, 82, 82 and 64% of cases, respectively. None of the cases showed mutation of exons 9, 11, 13 and 17 of the c-kit gene. The important feature of pigmented microcystic chromophobe renal cell carcinoma is a relatively benign biological behavior and the absence of distant metastases and sarcomatoid transformation.

Myths and misconceptions about chronic constipation

There are many strongly held beliefs about constipation that are not evidence based. The purpose of this review is to address these beliefs concerning various aspects of constipation. There is no evidence to support the theory that diseases may arise via "autointoxication," whereby poisonous substances from stools within the colon are absorbed. Dolichocolon, defined as an elongated colon, should not be seen as a cause of constipation. The role of sex hormones altering gut function during the menstrual cycle appears to be minimal. During pregnancy they may play a role in slowing gut transit. Hypothyroidism can cause constipation, but among patients presenting with constipation, hypothyroidism is rare. A diet poor in fiber should not be assumed to be the cause of chronic constipation. Some patients may be helped by a fiber-rich diet but many patients with more severe constipation get worse symptoms when increasing dietary fiber intake. There is no evidence that constipation can successfully be treated by increasing fluid intake unless there is evidence of dehydration. In the elderly constipation may correlate with decreased physical activity, but many cofactors are likely to play a role. Intervention programs to increase physical activity as part of a broad rehabilitation program may help. It is unlikely that stimulant laxatives at recommended doses are harmful to the colon. A proportion of patients with chronic constipation is dependent of laxatives to achieve satisfactory bowel function, but this is not the result of prior laxative intake. Tolerance to stimulant laxatives is uncommon. There is no indication for the occurrence of "rebound constipation" after stopping laxative intake. While laxatives may be misused, there is no potential for addiction.

Effects of long-term administration of Senna occidentalis seeds in the large bowel of rats

Plants of the genus Senna that contain anthranoides derivatives are frequently used as cathartics. Radiological studies have demonstrated that patients with chronic constipation who have used stimulant laxative have colonic redundancy and dilatation more frequently than patients who have not. The objective of the present work was to study morphological and histochemical changes of the lower gut after administration of Senna occidentalis seeds for a long period to rats, as observed in skeletal muscle fibers. Fragments of the lower gut of young and adult rats treated with S. occidentalis seeds (2% for 171 days and 3% for 61 days in the diet) were submitted to histological and histochemical analysis and to densitometry. The most important finding was decreased oxidative enzyme activity in smooth muscle cells and in myenteric neurons of the large bowel. As oxidative metabolism is essential for ATP and energy production, these results suggest that the functional intestinal disturbance caused by the chronic use of Senna occidentalis as a laxative can be due to a metabolic effect involving energy production, which would decrease colonic motility and cause functional colonic dilatation, but without any irreversible anatomic change.

Pathology of drug-associated gastrointestinal disease

A large number of drugs have gastrointestinal side-effects of which diarrhoea or constipation, nausea and vomiting are amongst the commonest. In relatively few are there diagnostic pathological changes and this review draws attention to the most common. Incriminating a drug as a cause of specific pathological changes requires the drug to be associated with the changes, for the latter to resolve when the drug is withdrawn and for them to re-appear when a patient is rechallenged with the drug. Individual histological features such as apoptosis, tissue infiltration by eosinophils and increased intra-epithelial lymphocytes within the gut mucosa can be clues to an iatrogenic aetiology but these are by no means specific. Amongst the few pathognomonic patterns of drug reactions is pseudomembranous colitis and diaphragm disease. These, along with others such as reactive gastritis and the collagenous and lymphocytic forms of microscopic colitis, in which drugs have also been implicated, are described here.

Melanosis of the appendix: common in the paediatric age group

AIMS

To investigate the incidence of melanosis of the vermiform appendix in a paediatric population, and look for correlations with season, apoptotic rate and inflammation as possible causes.

METHODS AND RESULTS

We examined 300 appendices removed for abdominal pain and incidentally during other procedures over the period January 1996 to March 1999. Melanosis was present in 46% of adequate specimens with an even distribution between sexes and age groups. The two older age groups had a relatively higher incidence of severe involvement compared with the younger age group, although the difference was not statistically significant. We attempted to correlate the presence of melanosis with the season of the year and the peak incidences of paediatric gastrointestinal disease but could find no relationship. No statistically significant correlation was found between apoptotic rate and the presence of melanosis.

CONCLUSIONS

The findings suggest melanosis of the appendix is relatively common. It is probably due to apoptosis associated with increased epithelial cell turnover due to many differing causes including infection, with purgative ingestion probably involved in only a minority of paediatric cases.

Colonic lymphoid hyperplasia in melanosis coli

We describe the case of a patient with Rett syndrome, a syndrome characterized by progressive infant encephalopathy, developmental delay, dementia, autism, ataxia, microcephaly, spastic paraparesis, and autonomic neuropathy with constipation. At colonoscopy, multiple foci of tiny white, sessile, polypoid lesions were seen throughout the colon and rectum, mimicking the appearances of small hyperplastic or adenomatous polyps, associated with generalized melanosis coli. This is the first case to our knowledge describing melanosis coli in a patient with Rett syndrome. As melanosis pigment deposition is characteristically not seen in lymphoid tissue, the lymphoid tissue was identifiable at endoscopy as multiple white nodules mimicking generalized colonic polyposis throughout the colon. We discuss the likely mechanisms of lymphoid hyperplasia and coexistent melanosis coli in Rett syndrome.

What is the significance of muciphages in colorectal biopsies? Muciphages and other mucosal accumulations in the colorectal mucosa

Muciphages (mucin-containing macrophages), first described in 1966 by Azzopardi & Evans, are a common feature of biopsies of large intestinal mucosa, even in the absence of other abnormalities such as active inflammation or evidence of chronic inflammatory bowel disease. Should they be mentioned in diagnostic reports? Do muciphages reliably indicate previous mucosal disease, now quiescent? In the following articles, Salto-Tellez & Price review what is known about muciphages and conclude that they reflect previous occult and clinically unimportant mucosal damage and that, in an otherwise normal colorectal mucosa, they have no diagnostic significance; and Shepherd draws attention to a wide range of clinically much more significant mucosal infiltrates that could be mistakenly regarded as muciphages and thus overlooked.

Melanosis thyroidi

Despite many studies on melanosis thyroidi, there is no consensus concerning the nature of the pigment or its pathogenesis. Here the past literature on this subject is reviewed and results are reported on a case of melanosis thyroidi that provides fresh insight into the nature of the pigment and its genesis. Briefly, the conclusion is that while a few of the pigment granules are classic lipofuscin granules (i.e., single-membrane-bound structures containing electron-dense material in the form of particles, granules and masses, and electron-lucent lipid droplets), a majority of the pigment granules also contain colloid, which is easily identified by its particulate substructure similar to the colloid in the lumen of follicles. Thus, these pigment granules are, in fact, ambilysosomes, where degradation of both endogenous (organelles) and exogenous (colloid) material occurs. Several phagosomes containing colloid were also seen in the thyroid epithelial cells.

Carney complex, Peutz-Jeghers syndrome, Cowden disease, and Bannayan-Zonana syndrome share cutaneous and endocrine manifestations, but not genetic loci

Carney complex (CC), Peutz-Jeghers syndrome (PJS), Cowden disease (CD), and Bannayan-Zonana syndrome (BZS) share clinical features, such as mucocutaneous lentigines and multiple tumors (thyroid, breast, ovarian, and testicular neoplasms), and autosomal dominant inheritance. A genetic locus has been identified for CC on chromosome 2 (2p16), and the genes for PJS, CD, and BZS were recently identified; genetic heterogeneity appears likely in both CC and PJS. The genes for PJS and CD/BZS, STK11/LKB1 and PTEN, respectively, may act as tumor suppressors, because loss of heterozygosity (LOH) of the PJS and CD/BZS loci has been demonstrated in tumors excised from patients with these disorders. We studied 2 families with CC in whom the disease could not be shown to segregate with polymorphic markers from the 2p16 locus. Their members presented with lesions frequently seen in PJS and the other lentiginosis syndromes. We also tested 16 tumors and cell lines established from patients with CC for LOH involving the PJS and CD/BZS loci. DNA was extracted from peripheral blood, tumor cell lines, and tissues and subjected to PCR amplification with primers from microsatellite sequences flanking the STK11/LKB1 and PTEN genes on 19p13 and 10q23, respectively, and a putative PJS locus on 19q13. All loci were excluded as candidates in both families with LOD scores less than 2 and/or by haplotype analysis. LOH for these loci was not present in any of the tumors that were histologically identical to those seen in PJS. The overall rate of LOH for the PJS and CD/BZS loci in tumors from patients with CC was less than 10%. We conclude that despite substantial clinical overlap among CC, PJS, CD, and BZS, LOH for the STK11 and PTEN loci is an infrequent event in CC-related tumors. Linkage analysis excluded the PJS and CD/BZS loci on chromosomes 19 (19p13 and 19q13) and 10 (10q23) from harboring the gene defect(s) responsible for the phenotype in these 2 families.

Pigmented microcystic chromophobe cell carcinoma: a unique variant of renal cell carcinoma

Five cases of pigmented chromophobe renal cell carcinoma are presented. The patients included four men and one woman between the ages of 60 and 73 years (median age, 66.5 years), who presented with symptoms due to their renal mass. Surgical resection of the renal mass was performed in all patients. Grossly, the tumors were well encapsulated, yellow to dark gray, with a vague nodular pattern on cut surface. The tumors varied between 2.5 and 9 cm in greatest diameter. Histologically, all tumors shared similar features, namely, a malignant cellular proliferation composed of deeply eosinophilic to clear cytoplasm with round nuclei and inconspicuous nucleoli. The cellular proliferation was arranged in a microcystic and/or microalveolar pattern. In one tumor, conventional areas of clear cell carcinoma in association with the chromophobe component were present. In addition, all tumors contained pigmented areas, which were shown by light microscopy to have features of lipochrome pigment. Ultrastructural studies of these areas demonstrated the presence of intracytoplasmic polygonal to round, electron-dense pigment granules, which in some areas seemed to coalesce to form larger granules. In addition, numerous mitochondria and cytoplasmic vesicles were present. The cases described herein highlight an additional morphologic variant of chromophobe renal cell carcinoma.

Melanosis coli in inflammatory bowel disease

Melanosis coli is a relatively common condition in which pigment is deposited in macrophages in the colonic lamina propria. The association with anthraquinone laxatives is well described, but melanosis coli has also been described in patients not using these agents. We report 25 patients with inflammatory bowel disease and melanosis coli, 5 (20%) of whom had documented laxative use. Most patients had ulcerative colitis (72%) or Crohn's colitis (24%), and the mean duration of inflammatory bowel disease was more than 7 years. These data raise the possibility that chronic colitis could cause melanosis coli even in the absence of laxative use.

As you like it

I have developed something of a reputation for criticizing freely and frequently at our meetings and in my writings. You say you like this and find it useful and entertaining. As you like it, you are welcome to more of it. My comments and criticisms are presented under the following headings: (1) criticize at your peril; (2) how it all started (unjustly accused!); (3) abbreviations (a source of perennial aggravation, confusion, and waste of time); (4) mysterious bodies in mesotheliomas; (5) call a crystal a "crystal," not a "crystalloid"; (6) electron microscopy-a study of osmium artifacts; (7) length-to-diameter ratio of microvilli (mission impossible); (8) lamellar bodies (a popular but debased term); (9) amyloid filaments, not fibers; (10) filaments and microtubules do not branch; (11) there is no such thing as pseudomelanosis; (12) botched histochemistry (just about every gastrointestinal tract pigment was misdiagnosed by histochemistry); (13) intranuclear Russell bodies, not "Dutcher bodies"; and (14) nuclear pores and virus-like particles (a new development in an old farce).

Selective uptake of intraluminal dextran sulfate sodium and senna by macrophages in the cecal mucosa of the guinea pig

The involvement of macrophages in the passage of intraluminal substances into the lamina propria was examined in the large intestine of the guinea pig. Dextran sulfate sodium (DSS) and senna, which, experimentally, induce ulcerative colitis and melanosis coli, respectively, were chosen for examination, since these substances are visible under the microscope without any special treatment. DSS (MW 50,000) and senna were orally administered to guinea pigs. In tissue sections of the intestine, the presence of DSS was demonstrated by toluidine blue staining, while senna was visible under the light microscope as brown pigment. In the large intestine of guinea pigs, macrophages were most numerous in the cecum, decreasing in number towards the rectum. Metachromatic reaction due to DSS was first recognized in the epithelium of the cecum, and was subsequently incorporated by macrophages. The presence of DSS, either in the epithelium or in macrophages, was not recognized in the small intestine or the distal colon. Senna pigmentation was also limited to the cecum and proximal colon, in which pigmented macrophages aggregated in the lamina propria. The two different substances administered orally were taken up in the cecum, and partly also in the proximal colon; the substances passed through the epithelium and were incorporated by macrophages. This finding suggests the existence of a weak point in the intestinal barrier in this particular portion of the intestine.