Hair Preparations
Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.3 One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.16 Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.4
Final Thoughts
Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.