Friday, November 3, 2017

Fungal Infection of Nails

Fungal infection of the nails has been classified into four types :

1. White superficial onychomycosis presents with diffuse or speckled white discoloration of the surface of the toenails. It is caused primarily by Trichophyton mentagrophytes, which invades the nail plate. The organism may be scraped off the nail plate with a blade, but treatment is best accomplished by the addition of a topical azole antifungal agent.

2. Distal subungual onychomycosis presents with foci of onycholysis under the distal nail plate or along the lateral nail groove, followed by development of hyperkeratosis and yellow-brown discoloration. The process extends proximally, resulting in nail plate thicken and separation from the nail bed. Trichophyton rubrum and, occasionally, T. mentagrophytes infect the toenails; fingernail disease is almost exclusively due to T. rubrum, which may be associated with superficial scaling of the plantar surface of the feet and often of one hand. These dermatophytes are found most readily at the most proximal area of the nail bed or adjacent ventral portion of the nail plates that are involved. Topical therapies such as ciclopirox 8% lacquer may be effective for solitary nail infection. Because of their long half-life in the nail, terbinafine or itraconazole may be effective when given as pulse therapy (1 wk of each mo for 3–4 mo). Either agent is superior to griseofulvin, fluconazole, orketoconazole. The risks, the most concerning of which is hepatic toxicity, and costs of oral therapy must be weighed carefully against the benefits of treatment for a condition that generally causes only cosmetic problems.

Wednesday, November 1, 2017

Screening and Diagnosis of Celiac Diseases

Screening for celiac disease has been recommended for specific risk factors.

The anti-endomysium IgA antibody and anti-tissue transglutaminase IgA antibody tests are highly sensitive and specific in identifying individuals with celiac disease.

The anti-endomysium IgA antibody test is an immunofluorescent technique and is relatively expensive; interpretation is operator dependent and prone to errors so that it has largely been replaced by anti-tissue transglutaminase IgA antibody tests, which are simpler to perform and have similar sensitivity and specificity.

Anti-gliadin IgA and IgG and anti-reticulin IgA antibody tests are no longer recommended tests due to lack of specificity.

The anti-endomysium IgA and anti-tissue transglutaminase IgA antibody test can be falsely negative with IgA deficiency, which is associated with an increased incidence of celiac disease. Measurement of serum IgA concentration is mandatory to assure that false-negative results in IgA-deficient individuals are excluded. If celiac disease is suspected in patients with IgA deficiency, intestinal biopsy may be required. Because screening with antibodies may identify patients without documented celiac disease on biopsy, it is important to set the lower limit of antibody titers high enough to avoid false-positive results.

A. Normal
B. Celiac disease

Small Intestinal Biopsy.

Definitive diagnosis of celiac disease requires small intestinal biopsy, as none of the available serologic tests are 100% reliable. The characteristic histologic changes include partial or total villous atrophy, crypt elongation and decreased villous/crypt ratio, increased number of intraepithelial lymphocytes, intraepithelial lymphocyte mitotic index >0.2%, decreased height of epithelial cells, and loss of nuclear polarity. The mucosal involvement can be patchy, so multiple biopsies must be obtained.