A 34-year-old male presents with progressive thinning and wants to receive a hair transplant. During his examination you note the lesion above. He first noticed it five years ago and claims it has been growing slowly over the past few years. It is not painful.
Question 1: What is the most likely diagnosis?
- Epidermoid cyst
- Trichilemmal cyst
- Wen
- Pilar cyst
- Sebaceous cyst
Answer: B, C, D. Trichilemmal cyst, wen, and pilar cyst all describe the same lesion. Given the smooth appearance, lack of a visible pore, and location on the scalp, this is the most likely diagnosis.
Question 2: What is the difference between a pilar cyst and an epidermoid cyst clinically?
- Epidermoid cysts are primarily on the scalp
- Pilar cysts are primarily on the scalp
- Epidermoid cysts are often on the face
- Pilar cysts are often on the face
- Epidermoid cysts are often on the neck and trunk
- Epidermoid cysts have a central punctum
- Pilar cysts have a central punctum
Answer: B, C, E, F. Pilar cysts are primarily on the scalp, while epidermoid cysts are often on the face, neck, and trunk. Epidermoid cysts often have a central punctum, while pilar cysts do not. Pilar cysts are often familial and may be inherited in an autosomal dominant pattern.
Question 3: What is the difference between a pilar cyst and an epidermoid cyst histologically?
- Pilar cysts originate from the infra-infundibulum of the hair follicle and epidermoid cysts originate from the acro-infundibulum
- Epidermoid cysts originate from the infra-infundibulum of the hair follicle and pilar cysts originate from the acro-infundibulum
- Pilar cysts originate at the insertion of the arrector pili muscle.
- Both epidermoid and pilar cysts originate at the insertion of the arrector pili muscle.
Answer: A. Pilar cysts originate lower in the hair follicle (compared to epidermoid cysts). This partially explains why it has little epidermal attachment as it grows and can be more easily removed. It also explains why there is no visible pore (in contrast to epidermoid cysts). Pilar cysts are less prone to rupture since they have stronger walls. Epidermoid cysts, in contrast, are more likely to rupture, releasing highly inflammatory keratin. This causes scarring and the cyst to be bound down to the surrounding tissues.
Question 4: When should you remove scalp cysts?
- Scalp cysts should be removed as soon as possible
- You should remove them when they become bothersome, start to grow, or become painful.
- A scalp cyst should be removed after it has been present for several years when the capsule is thicker, making it less likely to pop so it can be removed in its entirety.
Answer: A. It is best to remove scalp cysts as soon as they are noticed, so that they will be easier to remove, the scar will be smaller, and there will be less hair loss. As a cyst grows, it compresses the surrounding hair follicles and can cause permanent alopecia. Early cysts are more easily removed than older cysts which often are more adherent to the surrounding tissue. Infected cysts should be incised and drained and then removed once the infection has subsided.
Question 5: What is the best way to remove pilar cysts?
- Pilar should be incised and drained and then allowed to scar down before excising.
- Pilar cysts should be injected initially with a corticosteroid to shrink them and then excised.
- They should be removed through a linear incision made with a number 11 or 15 blade
- They should be removed through an elliptical incision just large enough to undermine and remove the intact cyst capsule
- They should be removed through a punch incision centered over the pore
Answer: C. The best way to remove a scalp cyst is through the smallest possible linear incision made with a #11 or #15 blade. The incision should be large enough to insert a small, curved Mosquito clamp. The clamp is used to remove the cyst in pieces. Care must be used to remove the entire cyst to prevent recurrence. A punch is not needed as there is no pore to remove and will cause more scarring. This contrasts with the excision of an epidermoid cyst, where failure to remove the pore will likely result in recurrence. No attempt should be made to remove a pilar cyst intact as this necessitates using a larger incision and will cause unnecessary scarring.
Question 6: How will you close the defect created during the removal of a small to moderately sized cyst?
- One to three nylon vertical mattress sutures depending on the size
- Buried, dissolvable purse string suture(s)
- An absorbable or non-absorbable running stitch
- Absorbable, horizontal mattress sutures to eliminate the dead space and then nylon or Monocryl sutures to close
- Stainless steel staples
- Pack the dead space with sterile gauze and leave open
Answer: A. Closure of the dead space can be simply achieved with one or more (non-absorbable) vertical mattress stitches. The entry and exit points should be close to the wound edge. If placed properly, significant wound edge eversion will be achieved. Any distortion of the skin will disappear as soon as the sutures are removed. It is important not to tie any sutures until they have all been placed. The sutures should be removed in approximately 10 days. Make sure the knot is large enough to keep the suture from being buried. The defect from a very large cyst can be packed with Iodoform gauze, left to heal by secondary intention, and then excised at a future date using a small elliptical incision.
Question 7: How should the wound site be dressed?
- Duoderm and change every 2-3 days
- Topical Neosporin or Bactroban ointment, shower, and cover with a gauze bandage daily
- Dressing for day 1 (if needed) and then Vaseline only
Answer: C. Scars heal best when the epithelium remains moist, and a clean scalp wound rarely gets infected. Neosporin can be an allergen and mupirocin is expensive and unnecessary. Regular Vaseline is preferred. It may be useful to apply a bandage the first day to absorb any wound exudate, but then one can apply Vaseline alone to the sutures until they are removed.
If you are experiencing gradual hair thinning, please contact our office for an appointment. Call 212-826-2400 or schedule a consult here.
