Scalp Biopsy

Scalp biopsies can be used to make or confirm a diagnosis of alopecia and can be essential in guiding therapy. A four millimeter punch biopsy which includes subcutaneous fat is needed to ensure sampling of the entire follicular unit and any anagen follicles. Horizontal sections are becoming the method of choice for dermatopathologists as they offer the advantage of evaluating large numbers of follicles simultaneously, de termining hair density, telogen/vellus ratio, anagen to telogen ratio, and location of inflammatory infiltrate (Whiting, 1990).

 

The differential diagnoses for hair loss are grouped into three categories: disturbances of the hair cycle, damage to the hair shaft, or disorders affecting the follicle. The following is not meant to be an exhaustive review of possible causes of hair loss, but instead common causes of hair loss in woman are highlighted.

Disturbances of the Hair Cycle

Telogen effluvium: Normally the majority of scalp hair is in the growth phase, with a small percentage of hairs in the resting phase being shed daily (100-200 hair shed daily). Under certain circumstances a higher percentage of hairs cycle into the resting phase, and a woman may notice a sudden onset marked shedding. The exam usually reveals "normal" hair density and good scalp coverage on global exam, because more than 50% of the hair must be lost before hair loss is clinically apparent. If the patient is examined when the hair loss is still active, the pull test may be positive, otherwise hair regrowth with tapered ends may be seen. Common causes include high fever, childbirth, severe infections; severe "flu," severe chronic illness, major surgery, thyroid disorder, crash diets, inadequate protein, and certain drugs (Fiedler & Gray, 2003).

The shedding often starts months after the inciting cause but is always self-limited and reversible if the offending cause is corrected or resolved. Using the analogy that the hair cycle is much like a menstrual cycle may help the patient understand the biology of telogen effluvium. Furthermore reassuring her that the hair shaft and hair follicle are healthy and normal can give a positive focus to the visit.

Damage to the Hair Shaft

Hair breakage: Hair is comprised primarily of the protein keratin, which is the same substance that forms fingernails and toenails (Krause & Foitzik, 2006). Sulfur crosslinks provide for the strength of the hair. Damage to the hair shaft by improper cosmetic techniques can cause hair breakage. There is little damage from normal dyeing, bleaching, waving or straightening. However, breakage can occur with too much tension during waving; waving solutions left on too long; or improperly neutralized, waving, and bleaching on the same day or too frequently (Draelos, 2000). Other causes of hair breakage include excess tension in braids, ponytails, cornrows, or excess friction due to helmets or orthodontia (Callender, McMichael, & Cohen, 2004). On examination, patchy areas of short hair with blunt (broken) hair tips can be seen. A tug of the distal hair shafts yields multiple short segments of hair.

Treatment of hair breakage usually requires alteration of the hair care routine. Hairstyles that pull on the hair, like ponytails and braids, should be put in as loosely as possible and should be alternated with looser hairstyles. If there is a constant pull on the hair, damage to the hair follicle can occur, resulting in traction alopecia (see Figure 3), which is seen especially along the sides of the scalp. Shampooing, combing, and brushing too often can also damage hair, causing it to break. Recom mending a cream rinse, conditioner, or leave-in conditioner with silicone will make the hair more manageable and easier to comb. When hair is wet, it is more fragile, so vigorous rubbing with a towel, and rough combing and brushing should be avoided. Instead, the use of wide-toothed combs and brushes with smooth tips should be recommended. Also, using heat (blow-dryer, curling iron, flat iron) on wet hair can cause increased damage. Hair loss is reversible if the cosmetic procedure is stopped and the hair is handled gently; this is true even in early stages of traction alopecia. Stressing this reversibility should be the "take home message" for the office visit.

Please continue to next  page