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Gastroenterology

Clinical Articles

Evidence-based practice tips for IBS

An update on recent reviews, guidelines and studies that you can use now…

By Sophia Auld

Dermatology

Clinical Articles

Eczema – More Than Just an Itchy Rash

Eczema (eczematous inflammation) is the most common inflammatory disease of skin. These rashes are itchy and recognised by erythema, scale and vesicles, but can have secondary changes of infection, irritation or scratching. The term “dermatitis” is a broader, non-specific term which is not synonymous with eczema. There are three stages of evolution (acute, subacute and chronic) and numerous presentations depending on stage, age and aetiology. Histologically, the eczematous inflammatory processes have in common the spongiotic tissue reaction. Spongiosis refers to intra-epidermal oedema which resembles sponge.

Stages of eczema

Acute eczema

Clinical: Red, swollen, pebbly plaques. History of contact with specific allergen or chemicals. For the id reaction, the vesicles will occur at distant sites. Histology: Spongiosis, spongiotic vesiculation, intercellular oedema, perivascular dermal inflammation and occasional eosinophils.

Subacute eczema

Clinical: red, scaly lesions with indistinct borders, which may resemble psoriasis or fungal infections. Any allergic contact, asteatotic, atopic, nappy-related, chemical exposure, irritant contact, nummular, perioral-lick or stasis dermatitis may present this way. Histology: Less spongiosis and exocytosis (presence in the epidermis) of lymphocytes than acute form, and thickening (acanthosis) of the epidermis which may become psoriasiform. Parakeratosis, perivascular dermal inflammation and oedema are also present.

Chronic eczema

Clinical: Thick skin, skin lines accentuated (lichenified), fissures and excoriations. Caused by irritation of any subacute form, or appearing as lichen simplex chronicus. If the lichen simplex chronicus forms a local lump it is referred to as a prurigo nodularis. Histology: Hyperkeratosis, psoriasiform thickening of the epidermis, mild spongiosis, dermal mast cells and eosinophils. Lichen simplex chronicus will show marked hyperkeratosis, hypergranulosis, long epidermal ridges and vertical streaking of collagen in the dermis. Prurigo nodularis has thick, possibly excoriated, hyperkeratotic epidermis and marked dermal fibrosis and inflammation.

Specific types of eczema

Atopic dermatitis (atopic eczema)

Atopic dermatitis is an itchy, chronic relapsing skin disease which often start in childhood. There is a personal or family history of dry skin, eczema, hay fever, asthma and elevated serum IgE levels. There are essential and important clinical criteria, and the diagnosis requires exclusion of other conditions (e.g. scabies, contact dermatitis, psoriasis, photosensitive dermatosis). The pathogenesis and aetiology are not entirely clear and the disease is increasing in frequency.

Nummular dermatitis (discoid eczema)

Clinical: A chronic disorder of adults, of unknown aetiology, not related to atopy, but possibly to dry skin. Papules and papulovesicles coalesce to form nummular plaques 1-4 cm in diameter with oozing, crust, and scale. They are paler and les scaly than psoriasis. Most common sites of involvement are upper extremities, including the dorsal hands in women, and the lower extremities in men. Histology: Varies with duration. Spongiosis with mild acanthosis and exocytosis of inflammatory cells in earlier lesions. With time, the degree of acanthosis (thickening) increases. Additional features include scale-crust formation above the thickened epidermis and dermal perivascular inflammatory infiltrate.

Contact dermatitis

The substance could be an irritant or an allergen. Irritant (e.g. concentrated solvents, soaps) will cause a non-immunological reaction in any exposed person. Allergic reactions will occur in predisposed people on the basis of a delayed hypersensitivity reaction to a substance at low concentration and evolves rapidly at the site once sensitised. Occupational contact dermatitis is common and may be of irritant or allergenic (or both) types.

Irritant contact dermatitis

Commonly provoked by environmental substance e.g. contact with water, detergents and other chemicals where the epidermal barrier is compromised, and subsequently occurs most commonly on the hands, but any site where external stimuli could be suspected. Histology: Mild spongiosis, epidermal cell (keratinocyte) necrosis, and neutrophilic infiltration of the epidermis.

Allergic contact dermatitis

Clinical: Exposure to, and absorption of an antigen through skin. Most allergens are weak and there may be repeated exposure before sensitisation. The shape and location of the rash are the best clues. Histology: Subacute, chronic dermatitis or acute dermatitis may be seen. The dermal inflammatory infiltrate predominately contains lymphocytes and other mononuclear cells. Occasional atypical T-cell infiltrates may simulate mycosis fungoides.

Stasis dermatitis

Clinical: Occurring on the legs where venous drainage is impaired. However, most patients with venous insufficiency do not develop dermatitis. Unfortunately, topical medicines used in this situation seem to have many potential sensitising agents. Histology: Mild spongiosis, foci of parakeratosis and scale crust. Dermal changes are prominent with neovascularisation, haemosiderin deposition and varying degrees of fibrosis (depending on chronicity) and there is often ulceration.

Seborrhoeic dermatitis

Seborrhoeic dermatitis is a common and chronic disease which most commonly occurs on the scalp and face secondary to toxic substances produced by yeasts (malassezia), but with genetic and environmental factors contributing. Histology: Spongiosis at the side of a hair follicle, often with overlying scale crust, which may be acute, subacute or chronic depending on the lesion biopsied. Neutrophils within the epidermis or stratum corneum requires a search for yeast on a PAS stain. More chronic lesions show progressive psoriasiform hyperplasia of the epidermis with less spongiosis. Mild oedema of the papillary dermis with a mild superficial perivascular infiltrate of lymphocytes, histiocytes and neutrophils.

Asteatotic eczema

Asteototic eczema develops as the result of very dry skin. It is most common in the elderly and on the lower limbs. Histology: Usually a mild subacute spongiotic dermatitis. Compact and irregular stratum corneum. Id reaction Clinical: ‘Autoeczematisation’: generalised eczema in response to a localised dermatosis or infection at a distant site. Can be a pompholyx-like reaction affecting hands or more generalised papular eruption. Will resolve when the acute initiating process is controlled. Histology: Mimics that of the initial localised dermatosis or shows a spongiotic reaction with varied intensity. Mild dermal oedema and lymphocytic infiltration are seen. References: Thomas Habif, Clinical Dermatology 6th edition 2016, Elsevier, chapters 3-5 Weedon’s Skin Pathology, 4th edition, editor James W Paterson, Churchill Livingstone Elsevier A.Bernard Ackerman, Histological Diagnosis of Inflammatory Skin Diseases, 2nd edition, Williams & Wilkins Dermnet skin disease atlas at dermnet.com and Dermnet NZ online at dermnet.nz.org

General Practice Pathology is a new regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs. The authors provide this editorial, free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.

By Dr Jane Nankervis

Gastroenterology

Clinical Articles

The Gut Microbiome – Fad or The Future?

Which bacteria are colonising your gut is becoming increasingly important, Australian researchers say. More and more evidence is suggesting the gut microbiota has a significant role in both the cause and the cure of a wide range of gastrointestinal and hepatic diseases and conditions. According to a review in The Medical Journal of Australia, research shows that particular types of bacteria colonising the gut have been associated the development of inflammatory bowel disease (IBD), metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steato-hepatitis (NASH), obesity and diabetes. We know that the bowel starts to be colonised by bacteria in utero. The make-up of an individual’s gut microbiota then depends on factors such as mode of delivery, breast-feeding, diet, illness and exposure to antibiotics. By the age of three, the gut microbiota resembles that of an adult. Observational studies have suggested a strong association between alterations in the microbiota because of environmental factors, and an increased risk of diseases. For instance, IBD was very rare in traditional Chinese populations, but studies have shown exposure to Western diets and medicines from a young age has increased the prevalence of this disease. “Asian adults who migrate from countries of low prevalence to countries of high prevalence do not have an increased risk of developing IBD, but their children experience the IBD incidence of their new country of residence,” the review authors said. Stronger evidence comes from studies into the exact nature of bacteria colonising the gut. It appears both the specific bacteria and the diversity of bacteria are important in disease pathogenesis. “For example, the presence of Proteus species at the time of Crohn’s disease resection is associated with early disease recurrence, while the presence of Faecalibacterium prauznitzii is protective against recurrence,” they said. Researchers have also found significant differences in the microbiota of people who develop severe alcoholic hepatitis and those who maintain normal hepatic function despite drinking the same amount of alcohol. Most importantly in the investigation of the role of the gut microbiota, is the emerging evidence that by altering the bacterial colonies in the gut we can alter the course of the disease. The classic example of this, of course, was the discovery of Helicobacter Pylori as the cause of peptic ulcer disease with treatment of this, dramatically changing health outcomes. But since then a lot of the research focus has been on faecal microbiota transplants (or poo transplants as they are commonly known). Mice studies have shown that a mouse will become fat if given a transplant of faecal bacteria from a fat donor mouse. Similarly, a similar result has been shown in a single trial of FMT from lean to obese humans, lowering triglyceride levels and increasing insulin sensitivity. FMT has also been shown to be an effective therapy for recurrent C.difficile infection and in active ulcerative colitis. And while the application of FMT as a treatment continues to be explored, investigators are also looking at how the microbiota can be changed through dietary means and how this can be used therapeutically. While probiotics have not been shown to be effective in the majority of inflammatory diseases, an anti-inflammatory diet combined with liquid formulated enteral nutrition has shown some success in Crohn’s disease. In short, the review authors suggest that the current interest in the gut microbiome is justified and has the potential to provide important therapeutic options in the future. “Microbial manipulation is an effective therapy, likely to have broadening implications,” they concluded. Reference White LS, Van den Bogaerde J & Kamm M. The gut microbiota: cause and cure of gut diseases. Med J Aust. 2018 Oct 1; 209(7): 312-16. Available from: https://www.mja.com.au/journal/2018/209/7/gut-microbiota-cause-and-cure-gut-diseases doi: 10.5694/mja17.01067

By Dr Linda Calabresi

Diet and nutrition

Clinical Articles

Have you gone vegan? Keep an eye on these 4 nutrients

There are many reasons people go vegan, from wanting to be healthier, to reducing their environmental footprint, to concerns about animal welfare. No matter what the reason, many people find it difficult to meet the nutrient intake targets for specific vitamins and minerals while on a vegan diet. These include vitamin B12, iron, calcium, and iodine. Here’s how to make sure you’re getting enough of these vitamins and minerals while following a vegan diet.

1. Vitamin B12

Vitamin B12, or cobalamin, is essential for making red blood cells, DNA (your genetic code), fatty acids located in myelin (which insulate nerves), and some neurotransmitters needed for brain function. Vitamin B12 is stored in the liver, so a deficiency probably won’t happen in adults in the short term.

Symptoms of B12 deficiency

Symptoms of vitamin B12 deficiency include tiredness, lethargy, low exercise tolerance, light-headedness, rapid heart rate or palpitations, bruising and bleeding easily, weight loss, impotence, bowel or bladder changes, a sore tongue, and bleeding gums. Other symptoms related to the nervous system include a loss of sensation in the hands or feet, problems related to movement, brain changes ranging from memory loss to mood changes or dementia, visual disturbances, and impaired bowel and bladder control.

Testing for B12 deficiency

Your doctor may request a blood test to check your vitamin B12 status and determine whether indicators are in the healthy range.

Vegan food sources of B12

Vitamin B12 is abundant in animal foods including meat, milk and dairy products. For vegans, plant sources of vitamin B12 include some algae and plants exposed to bacterial action or contaminated by soil or insects. While traces of vitamin B12 analogues can be found in some mushrooms, nori or fermented soy beans, more reliable sources include vitamin B12-supplemented soy or nut “milks”, or meat substitutes. Check the nutrition information panel on the label for the the B12 content. Crystalline vitamin B12 added to these products can boost the B12’s absorption rate to a level similar to that from animal products.

2. Calcium

Calcium is needed to develop and maintain the skeleton bones, and is stored in the teeth and bones. It is also essential for heart, muscle and nerve function.

Testing for calcium deficiency

Low calcium intakes are associated with osteoporosis or “brittle bones” and a higher risk of bone fractures. A bone scan is used to measure bone density, with osteoporosis diagnosed when bone density is low. Both low calcium intakes and low vitamin D levels increase the risk of osteoporosis. Check your bone health using the Know Your Bones online quiz.

Vegan food sources of calcium

Although the richest sources of calcium are milk and milk-based foods, vegans can get calcium from tofu or bean curd, some fortified soy or nut beverages, nuts, seeds, legumes, and breakfast cereals. Calcium needs can be higher for vegans and vegetarians due to the relatively high oxalic acid content of foods such as spinach, rhubarb, beans, and the high phytic acid content of seeds, nuts, grains, some raw beans, and soy products. These specific acids can lower the calcium absorption from these foods by 10-50%. In a study of calcium intakes of 1,475 adults , vegans were below national recommendations and had lower calcium intakes compared with vegetarians, semi-vegetarians, pesco-vegetarians, and omnivores.

3. Iodine

Iodine is needed to make thyroxine, a thyroid hormone used in normal growth, regulation of metabolic rate, and development of the central nervous system. Iodine is concentrated in the thyroid gland.

Symptoms of iodine deficiency

Iodine deficiency can lead to the enlargement of the thyroid gland, a goitre, or hypothyroidism. Symptoms of hypothyroidism include lethargy, tiredness, muscular weakness, feeling cold, difficulty concentrating, poor memory, weight gain, depression, facial puffiness, hair loss, dry skin, constipation, and slower heartbeat. In women, iodine deficiency can increase risk of miscarriage and stillbirth, and congenital anomalies, including mental retardation and cretinism.

Testing for iodine deficiency

Your iodine status can be assessed by a range of tests, including thyroid hormones in your blood, the size of your thyroid gland, or the presence of a goitre. Talk to your doctor about these tests.

Vegan food sources of iodine

The iodine content of food depends on the iodine content of plants, which in turn depends on soil iodine content. When soil content is low, iodine may need to be supplemented. Major sources of iodine are seafood, dairy products, and eggs. For vegans, iodised salt, commercial bread made using iodised salt, fortified soy or nut milks (check the product label) and seaweed are important. Substances called goitrogens, which are found in brassica vegetables – including cabbage, broccoli and Brussels sprouts, sweet potato and maize – can interfere with the production of thyroid hormones.

4. Iron

Iron is needed to make haemoglobin in red blood cells, which carries oxygen around your body. Iron is also needed for the production of energy in your muscles, and for concentration and a healthy immune system.

Symptoms and testing for iron deficiency and anaemia

Not having enough iron leads to iron deficiency, and is associated with reduced work capacity, impaired brain function, lower immunity, and delayed development in infants. The first stage of iron deficiency is referred to as low iron stores and your doctor may refer you for a blood test to check your iron status.

Vegan food sources of iron

In Australia and New Zealand, the biggest contributors to iron intake are wholegrain cereals, meats, chicken, and fish. The amount of iron absorbed from food depends on a person’s iron status (with those who are iron-deficient absorbing more), as well as the iron content of the entire meal, and whether iron is haem (from animal foods) or non-haem iron from plant sources such as grains and vegetables. Although iron from plant sources is less able to enter the body, you can boost your absorption by adding lemon or lime juice (citric acid) or other vitamin C-rich vegetables and fruits, which convert non-haem iron to a form than is better absorbed. Take care with food components that inhibit absorption of both haem and non-haem iron, including calcium, zinc and phytates in legumes, rice and other grains, and polyphenols and vegetable proteins that can inhibit absorption of non-haem iron. Long-term vegans will also need to keep an eye on levels of vitamin D, omega-3 fat and protein. A good strategy is to check in with your GP periodically to review your health and well-being, and an accredited practising dietitian can check whether you’re getting all the nutrients you need. This article is republished from The Conversation under a Creative Commons license. Read the original article.

By Prof Clare Collins