Pilonidal Disease

First of two entities in Part II, Chapter 16 (this chapter is split into two pages — pilonidal disease and Hidradenitis Suppurativa — as genuinely distinct clinical entities, per this wiki's established split rule). An acquired chronic, suppurative condition of the sacrococcygeal natal cleft, ranging from quiescent asymptomatic sinuses to active purulent infection. Estimated ~70,000 cases/year in the natal cleft alone; can also occur in other hair-bearing friction sites (interdigital web spaces of hairdressers/dog groomers, the umbilicus). Traditionally considered more common in males, but data suggests near-equal risk (up to 55% female in some series). Historically termed "jeep disease" from its high incidence among WWII jeep drivers (prolonged-sitting theory).

Etiology

Underlying etiology remains debated: previously thought congenital (inherited dorsal-midline malunion with embryologic remnants), now leading hypothesis is acquired — occurring in the natural environment of the natal cleft (warmth, repeated friction, moisture), where trauma to skin and surrounding hair follicles triggers a granulomatous foreign-body reaction to embedded hair, forming inactive sinuses or active infection. Risk factors: obesity, hirsutism, poor hygiene, prolonged sitting/driving, excessive sweating, deep natal cleft anatomy, family history.

Diagnosis

Presentation ranges from asymptomatic incidental pits to active infection with pain/drainage. Patients often mistakenly report "hemorrhoidal" bleeding (unrelated to bowel movements, spontaneous) or are referred with a suspected anal fistula diagnosis (natal-cleft pits rarely track to the anal canal and this is typically ruled out on exam). Diagnosis is clinical: exam reveals one or several midline pits, often containing debris/hair tufts removable with a hemostat; an acute abscess presents as a raised, erythematous, fluctuant, tender area — usually just lateral to the midline but sometimes at a distance, communicating with a nearby pit. No formal classification system exists, and no head-to-head comparison of all available treatments exists — procedure choice is largely driven by surgeon preference/familiarity rather than validated guidelines.

Treatment

A guiding principle across all treatment discussion: treatment should not be more debilitating than the disease itself. Postoperative complication rates are relatively high regardless of strategy chosen (mainly wound infection and chronic wound-care burden), and this should be discussed with patients upfront.

Nonsurgical

Quiescent disease needs no invasive treatment. Risk-factor modification: improved hygiene, weight loss, hair removal (shaving, waxing, depilatory creams, or laser — laser works best in light-skin/dark-hair patients and has limited/heterogeneous supporting data; recurrence 0–28%, lower than non-laser hair removal). Depilatory creams/laser are not recommended during active infection/ulceration. Postoperative hair removal (even after operative treatment) decreases recurrence.

Antibiotics are not typically indicated but may be adjunctive with extensive surrounding cellulitis/systemic sepsis signs, or in diabetic/immunosuppressed/prosthetic-device patients (typical regimen: third-generation cephalosporin + metronidazole). For an acute abscess, antibiotics are never sole treatment — incision and drainage is indicated.

Phenol — nonsurgical outpatient ablation: local anesthesia, tract debridement/enlargement, then 1–3mL crystallized phenol instilled into the cavity (surrounding skin protected with ointment) to cauterize and denature hair-associated tissue without pain. Overall success 62–95%, complications 0–2%; typically 1–4 sessions needed. Higher success when combined with laser hair removal or depilatory creams; effective even for recurrent disease.

Fibrin glue (or thrombin gelatin matrix) — similar concept to phenol: hair/debris curetted from the sinus, then fibrin glue instilled as a sealant to allow clot formation. Recurrence 0–17% (absent infection); one series reported 96% success with 79% patient satisfaction (dissatisfied patients required further treatment for failure). Another series: 27% recurrence at median 4 months, rising to 96.6% success after a second application. Also used as an adjunct with advanced flap procedures (durability unknown). A 2017 meta-analysis of 4 RCTs (253 patients) found only low-quality evidence for fibrin glue as monotherapy or flap adjunct — true utility remains unclear.

Surgical

Incision and drainage — acute pilonidal disease is defined as an abscess with/without associated cellulitis; regardless of chronicity, an acute abscess should be incised and drained, with the incision placed off the midline over the point of maximum fluctuance. Unroofing the cavity (not just draining it) and avoiding premature skin-edge apposition/healing are key to durable resolution; recurrent infection is typically from failure to address underlying hair/debris/granulation tissue, not from I&D itself.

Lay open technique (vs. excision with primary closure) — a fistula probe identifies the tract extent, an incision is made over the probe (electrocautery), the overlying skin excised to create a shallow wound (preventing premature surface healing), the tract debrided (curettes/cautery), and wound edges optionally marsupialized (running absorbable suture) to shrink/shallow the defect; heals by secondary intention with gauze dressing (no true packing). Success for initial operation up to 97%. Recurrence 8.8% (incised-and-left-open abscess) to 20.8% (excised-and-left-open). Postop infection rates similar to primary closure, but recurrence significantly less likely with lay open than primary closure. Lay open requires more intensive wound care (twice-daily dressing changes, often needing family assistance) and can produce hypertrophic granulation tissue requiring office cauterization.

Excision with primary closure — entire pilonidal cavity excised down to the sacral fascia, irrigated, closed in layers (absorbable deep sutures, nylon/polypropylene vertical mattress skin closure), often with a buttressing pressure dressing for several days to prevent seroma. Faster healing and less time off work than lay open, but higher postop infection risk requiring possible wound reopening. A Cochrane review (26 trials, 2530 patients) found faster healing times with primary closure but no infection-rate difference; off-midline closure had decreased infection rates and faster healing vs. midline closure — if primary closure is chosen, keep it off the midline.

Complex surgical treatment (flap-based)

No formalized guidelines for when complex/flap treatment is indicated after acute I&D. Goal: excise diseased tissue, cover the defect with healthy tissue, and raise/flatten the natal cleft anatomy. Generally considered for chronic sinuses with extensive epithelialized granulation tissue unresponsive to hygiene/hair removal, or for patients who have undergone multiple abscess-drainage procedures. Typically elective/scheduled surgery.

• Karydakis flap — elliptical excision ~2cm off midline down to sacral fascia (including all pilonidal pits); a flap of skin/subcutaneous tissue from the opposite side is raised and advanced over the resection bed, closed in layers (absorbable deep/sacral-fascia sutures, nonabsorbable vertical mattress skin closure), pressure dressing with tie-over sutures left 10–12 days. Good results: 6545-case Karydakis series reported 8% wound complications, <2% recurrence. More recent trials show morbidity up to 21%; comparative trial vs. secondary-intention healing showed 1.2% wound-complication and 18.7% recurrence rates; another study found 3% 1-year recurrence with 10% wound dehiscence; another found 8.1% wound complications and 2.7% recurrence.
• Rhomboid flap (Limberg flap) — rotational flap: excision site mapped in a rhomboid shape encompassing the pits, excised down to sacral fascia, flap raised and rotated into place, secured in layers over a drain. Conflicting results: wound infection 1.5–4%, recurrence 0–4.9% in some series; but complications as high as 49% (45% dehiscence, 4% infection, 13% recurrence) in another. Another study: 19.7% overall morbidity, 1.6% recurrence. Downside: more cosmetically noticeable scarring than other flaps.
• Cleft lift flap (Bascom procedure) — designed to "lift" the natal-cleft concavity and create an off-midline closure. A "safety zone" (max lateral dissection extent) and scimitar-shaped incision are marked with the patient prone; flap raised toward the opposite side before excision of diseased tissue (unlike other flaps, does not require excising the entirety of diseased tissue); central scarring lanced to free contracture; closed over a 7mm closed-suction drain, off the midline. Unlike other flaps, does not require excising all diseased tissue. Initial Bascom/Bascom series: 90% success, 100% after further procedures in the remainder; follow-up study 96% healing; further studies replicated 97% healing. High patient satisfaction, low recurrence, but postop morbidity up to 20%.

Minimally invasive treatments

Desirable given the major morbidity of open flap surgery.

• Endoscopic/video-assisted ablation of pilonidal sinus (VAAPS) — 4mm hysteroscope inserted after the cavity opening is saucerized; sinus/lateral tracts identified under continuous saline infusion with mechanical adhesiolysis; hair removed with grasping forceps; cavity ablated with a 5F bipolar electrode; residual cavity debrided and iodine-instilled. High healing rates/patient satisfaction; a prospective study (52-week median follow-up) found 67% success with 77% delayed healing rate. Recurrence reported lower than standard excisional operations. Compared to Limberg flap, endoscopic treatment may have higher recurrence but fewer postop complications. Modifications include intra-tract phenol injection.
• Laser ablation — outpatient diode-laser ablation of sinus epithelium promoting new granulation tissue; every pit must be treated. Return to daily activities/work immediately in up to 92.8% of patients; success ~85–90%, recurrence as low as 2.9%. Complications: pain, hematoma, abscess, drainage.
• Trephination — skin trephines (2.0–9.0mm) core out each pit; subcutaneous tract excision down to the cavity with 4.0–5.0mm trephines; acutely infected areas excised with 6.0–9.5mm trephines and left open to heal by secondary intent. Reported 89.7% healing at 4 weeks, 16.2% recurrence; postop complications <5%, wound infection <1%. Minimal wound care (light packing). Does not preclude future excisional flap procedures if recurrence occurs.

Management of recurrent disease

Recurrence remains prevalent regardless of technique: up to 34% at 1 year, 66% at 5 years. No formal guidelines exist for recurrent-disease management. For an acute abscess recurrence, I&D remains necessary regardless of prior treatment. After resolving the acute infection, evaluate recurrence extent; local wound-care efforts (silver nitrate for hypertrophic granulation tissue, warm soaks, soap cleansing) should be tried before extensive re-excision. Recurrence tends to be higher after antibiotic-only treatment and I&D-only treatment; up to 45% of recurrence patients are obese. For recurrence, local excision, flap-based procedures, or minimally invasive procedures may be considered.

Wound healing adjuncts

Small or large chronic wounds may require ongoing management (likely from repeated friction/movement in the natal cleft). After ruling out recurrent sepsis, and before extensive re-excision: silver nitrate for hypertrophic granulation, warm soak/soap cleansing, silver-impregnated gauze strips, hydrophilic wound dressing cream, or methylene blue/gentian violet creams (applied twice daily under a protective gauze dressing) can achieve definitive healing without further surgery.

Related pages

• Hidradenitis Suppurativa — the second entity covered in this same source chapter; distinguished on exam by the absence of midline pits (a key differentiator per that chapter's diagnostic discussion).
• Anal Stenosis — already listed "suppurative processes (complex abscess/fistula, hidradenitis)" in its differential; this page and Hidradenitis Suppurativa provide the fuller pilonidal/HS content that mention was gesturing at.

Open items / gaps

• No primary-literature source yet for the flap-technique comparative outcome data (Karydakis, Limberg, cleft lift) — all known only via this textbook chapter's synthesis of a fragmented, heterogeneous case-series literature that the chapter itself notes lacks head-to-head comparison.