Vulvar and Vaginal Pathology

BENIGN INFLAMMATORY AND INFECTIOUS LESIONS

• Vulvovaginitis mechanisms: Disruption of normal vaginal microbiota (lactobacilli) by antibiotics, hormonal changes, or immunosuppression allows proliferation of pathogenic organisms (Candida albicans, Trichomonas vaginalis, bacterial vaginosis consortium). Candida causes pseudohyphae and budding yeast within superficial epithelium with acute inflammatory infiltrate; bacterial vaginosis features loss of lactobacilli and overgrowth of anaerobes (Gardnerella vaginalis, Prevotella, Mobiluncus) with characteristic clue cells (vaginal epithelial cells with adherent bacteria obscuring cell borders).
• Bartholin cyst pathophysiology: Obstruction of Bartholin gland ducts (lined by transitional epithelium) leads to accumulation of mucoid secretions; if infected, results in acute suppurative inflammation and abscess formation. Secondary malignant transformation occurs when intestinal-type mucinous adenocarcinoma arises from metaplastic columnar epithelium within cysts.

HPV-RELATED NEOPLASTIC PATHWAY (Basaloid/Warty Differentiation)

• Persistent high-risk HPV infection (types 16, 18, 31, 33) integrates into host genome at E2 disruption sites, leading to uncontrolled expression of viral oncoproteins E6 and E7. E6 binds and degrades p53 tumor suppressor protein, while E7 inactivates retinoblastoma (Rb) protein and p21, resulting in loss of G1/S checkpoint control and unscheduled cellular proliferation.
• Vulvar intraepithelial neoplasia (VIN) and vaginal intraepithelial neoplasia (VaIN) develop through progressive dysplasia: replacement of normal stratified squamous epithelium with increased nuclear:cytoplasmic ratio, hyperchromatic nuclei, increased mitotic figures, and disorderly maturation. HPV-associated VIN demonstrates basaloid differentiation (crowded basal cells with minimal maturation) or warty/condylomatous differentiation (exophytic growth with koilocytic atypia).
• Koilocytic change: Characteristic HPV effect with perinuclear halos, irregular nuclear membranes, binucleation, and hyperkeratosis; represents cytopathic viral effect in intermediate and superficial epithelial layers.
• Progression to invasive carcinoma: Loss of normal basement membrane as intraepithelial neoplasm breaches the dermal-epidermal junction; invasive component demonstrates infiltrating nests and strands of malignant squamous cells with desmoplastic stromal response.

NON-HPV-RELATED PATHWAY (Differentiated VIN)

• Associated with chronic vulvar dermatosis (lichen sclerosus or lichen planus) rather than HPV infection; driven by mutation accumulation in p53 and other tumor suppressors independent of viral integration.
• Pathologically characterized by well-differentiated keratinizing squamous cell carcinoma with retained surface maturation but abnormal basal layer hyperplasia; associated with increased dermal fibrosis and chronic inflammation from underlying dermatologic condition.

DYSPLASTIC LESIONS OF SPECIAL TYPES

• Differentiated (simplex) VIN: Arises in setting of lichen sclerosus or lichen planus; shows hyperkeratosis, acanthosis, and atypical basal layer cells in a thin epithelium with prominent underlying inflammation and fibrosis. Represents non-HPV pathway with higher risk of rapid progression to invasive carcinoma.
• Squamous cell carcinoma, keratinizing type: Develops from differentiated VIN; demonstrates pearl formation (concentric keratin), intercellular bridges, and keratohyalin granules; generally HPV-negative and associated with older patients (mean age 60-70 years).

MELANOMA AND PIGMENTED LESIONS

• Vulva represents third most common site for cutaneous melanoma (after skin and lower extremities); arises from increased junctional activity of melanocytes with architectural disorder and cytologic atypia.
• Lenigo simplex vs. melanoma in situ: Lentigos show regular elongated rete ridges with increased single melanocytes in basal layer and normal maturation with depth; melanoma in situ demonstrates pagetoid spread (melanocytes dispersed throughout epithelium), asymmetry, irregular junctional nests, and loss of normal maturation.

INFECTIOUS CAUSES

• Human papillomavirus (HPV): High-risk types (16, 18, 31, 33, 35, 45, 52, 58) cause 90% of HPV-associated vulvar/vaginal cancers; transmitted sexually; risk factors include early sexual debut, multiple partners, immunosuppression, and smoking.
• Candida albicans: Vaginal candidiasis; predisposing factors include antibiotics (disrupting normal flora), diabetes mellitus, pregnancy, oral contraceptive use, and immunosuppression (HIV/AIDS, chemotherapy).
• Trichomonas vaginalis: Sexually transmitted protozoan causing trichomoniasis; increased risk in multiple sexual partners and lack of barrier protection.
• Bacterial vaginosis: Polymicrobial overgrowth (Gardnerella vaginalis, Prevotella, Mobiluncus, Atopobium); associated with douching, new sexual partners, multiple partners, and immunosuppression.
• Herpes simplex virus (HSV-1 and HSV-2): Causes painful vesicles and ulcerations; reactivation from latency in sensory ganglia; risk of neonatal transmission during vaginal delivery.

MALIGNANT AND PREMALIGNANT CONDITIONS

• Chronic vulvar dermatosis: Lichen sclerosus and lichen planus are strong risk factors for non-HPV-associated vulvar squamous cell carcinoma; prevalence of malignant transformation 4-6% for lichen sclerosus.
• Smoking: Independent risk factor for HPV-associated VIN and vulvar cancer; impairs immune surveillance and DNA repair.
• Immunosuppression: HIV infection, organ transplantation, and systemic corticosteroid use increase risk of persistent HPV infection and accelerated progression to malignancy.
• Vulvar intraepithelial neoplasia (VIN): Premalignant lesion with progression risk to invasive carcinoma of 3-43% depending on type and grade.

BENIGN CONDITIONS

• Bartholin cyst: Results from obstruction of gland ducts; occurs in reproductive-aged women; can become infected (abscess) or undergo malignant transformation.
• Hidradenitis suppurativa: Chronic inflammatory disorder of apocrine gland-bearing areas (axillae, groin, vulva); involves follicular occlusion, inflammation, and draining sinuses.
• Epidermal inclusion cysts: Result from implantation or entrapment of epithelium during trauma, episiotomy, or surgical procedures.

BENIGN INFLAMMATORY/INFECTIOUS CONDITIONS

• Cardinal symptom: Intense vulvar pruritus with vulvar erythema and edema
• Physical exam findings: White, cottage-cheese-like discharge; erythematous vulva with possible satellite lesions (small pustules/macules on surrounding skin); vaginal erythema and edema
• Lab correlate: KOH preparation showing pseudohyphae and budding yeast; positive vaginal culture on Sabouraud medium
• Associated with diabetes, antibiotic use, pregnancy, oral contraceptives

• Malodorous vaginal discharge with fishy smell (due to volatile amines produced by anaerobes)
• Gray-white, homogeneous vaginal discharge coating vaginal walls
• Vaginal pH > 4.5 (normal lactobacilli produce lactic acid, maintaining pH 3.8-4.5)
• Clue cells on wet mount (pathognomonic finding)

• Frothy, yellow-green vaginal discharge with vulvar pruritus and dysuria
• Vaginal erythema with possible "strawberry cervix" (punctate hemorrhagic spots on cervix from trichomonal trauma)
• Vaginal pH > 4.5
• Motile flagellated trophozoites on wet mount

• Painful vesicles progressing to shallow ulcerations with erythematous halos
• Severe dysuria, vulvar pain, and burning
• Vesicular fluid containing multinucleated giant cells on Tzanck smear
• Positive HSV PCR or viral culture

• Painless, fluctuant swelling in lateral vulva at 4-5 or 7-8 o'clock position (location of duct opening)
• If infected: Acute pain, erythema, and purulent drainage
• Mass typically 3-30 mm, mobile, arising from deep vulva

PREMALIGNANT CONDITIONS

• HPV-associated VIN: Pruritus, burning, pain, or asymptomatic (25% discovered incidentally)
• Visual appearance: White, red, or pigmented macules/patches; raised, warty, or flat lesions; may appear as multifocal lesions (especially in younger women with HPV-associated disease)
• Differentiated VIN: Often raised, scaling plaques associated with lichen sclerosus (thin, white epithelium) or lichen planus (violaceous papules with reticular pattern); primarily in older women (mean 60+ years)
• Colposcopy findings: Acetowhite lesions with punctation and mosaic patterns after acetic acid application (enhanced by colpomicroscopy)

• Often asymptomatic, discovered on cervical cancer screening
• Vaginal discharge, bleeding, or dyspareunia if symptomatic
• Visual findings: Red, warty, or pigmented lesions in vaginal vault
• Increased risk in women with history of cervical cancer or concurrent cervical intraepithelial neoplasia (CIN)

MALIGNANT CONDITIONS

• Pruritus, vulvar pain, bleeding, or ulceration (often long-standing)
• Raised, infiltrative ulcerated mass with irregular borders; may appear as warty or nodular lesion
• Younger patients (mean 45-55 years) with basaloid or warty morphology
• Lymphadenopathy if advanced disease (sentinel node assessment critical for staging)

• Chronic vulvar irritation, pruritus, and scaling from underlying lichen sclerosus or lichen planus
• Indurated, ulcerated plaque with irregular borders and possible central necrosis
• Older patients (mean 60-75 years); generally more aggressive biologically with poorer prognosis
• Advanced locoregional disease at presentation common

• Pigmented lesion with color variation, irregular borders, asymmetry (ABCDE criteria)
• Bleeding, itching, or changing appearance
• Typically in labia majora or minora; often missed or delayed diagnosis due to rarity and cultural hesitancy to examine area
• Poor prognosis due to thick lesions at presentation (mean Breslow thickness 8-10 mm vs. 1-2 mm for cutaneous trunk melanomas)

• Painless vulvar mass or cyst that fails to resolve or becomes symptomatic
• Mucoid discharge, bleeding, or pain if malignancy develops
• Adenocarcinoma (mucinous, intestinal type) arising from metaplastic columnar epithelium
• Delayed diagnosis common as mistaken for simple cyst

GENERAL DIAGNOSTIC APPROACH

Clinical Assessment

• Detailed vulvar/vaginal inspection under good lighting (speculum examination essential)
• Palpation of any lesions to assess depth, mobility, and associated lymphadenopathy
• Colposcopy with acetic acid application for magnified visualization and directed biopsy of suspicious lesions
• Photography recommended for documentation and comparison over time

BENIGN INFLAMMATORY CONDITIONS

• Microscopy: KOH preparation of vaginal discharge demonstrating budding yeast and pseudohyphae (septate filaments with budding cells)
• Gram stain: Gram-positive, oval budding yeast with hyphae
• Culture: Sabouraud dextrose agar (confirmatory when diagnosis uncertain)
• Vaginal pH: ≤4.5 (normal range); elevated pH suggests alternative diagnosis
• DNA probe or PCR: Available but typically reserved for recurrent infections

• Amsel criteria (3 of 4 required for diagnosis):

1. 1.Thin, gray-white, homogeneous vaginal discharge
2. 2.Vaginal pH > 4.5
3. 3.Positive "whiff test" (fishy amine odor when KOH added to discharge)
4. 4.Clue cells ≥20% on wet mount

• Gram stain: Gram-variable coccobacilli replacing normal lactobacilli; Nugent score ≥7 indicates bacterial vaginosis
• Molecular testing: PCR or nucleic acid amplification tests (NAATs) for Gardnerella vaginalis or Atopobium (increasingly used)

• Wet mount microscopy: Motile, pear-shaped flagellated trophozoites (15-20 μm) with characteristic jerky, twitching movement
• Vaginal pH > 4.5
• Nucleic acid amplification test (NAAT): Most sensitive and specific (>97% sensitivity, 99% specificity); gold standard
• Rapid antigen or DNA probe tests: Alternative point-of-care diagnostics

• Viral culture: Gold standard for HSV; culture taken from fluid of intact vesicle or ulcer base; positive culture in 2-7 days; **intranuclear

Infectious vulvovaginitis (CDC STI Treatment Guidelines, 2021)

• Azole antifungals: fluconazole 150 mg PO once for uncomplicated candidiasis; topical azoles (miconazole, clotrimazole) preferred in pregnancy because oral fluconazole is avoided. Recurrent disease is treated with induction followed by weekly suppressive fluconazole.
• Nitroimidazoles: metronidazole is first-line for both bacterial vaginosis and trichomoniasis; CDC now recommends a 7-day multidose course for trichomoniasis in women rather than a single 2 g dose. Sexual partners are treated in trichomoniasis but not in bacterial vaginosis. Clindamycin is the alternative for BV.
• Nucleoside analogues: acyclovir or valacyclovir for HSV, episodic for outbreaks and daily for suppression; they shorten shedding but do not eradicate latent ganglionic virus.

Lichen sclerosus (ACOG and dermatology society guidance)

• Ultrapotent topical corticosteroid: clobetasol propionate 0.05% ointment, nightly induction then maintenance — reduces pruritus, halts scarring, and lowers cancer risk.
• Topical calcineurin inhibitors (tacrolimus) are second-line steroid-sparing agents. Topical testosterone is not recommended.

Intraepithelial neoplasia (ASCCP/ACOG)

• HPV-associated high-grade VIN/VaIN: wide local excision, CO2 laser ablation, or topical imiquimod; ablation and topical therapy require biopsy first to exclude invasion.
• Differentiated VIN: excision only — its short latency to invasive keratinizing carcinoma makes ablative or topical management inappropriate.

Complications of chronic dermatoses

• Architectural scarring in lichen sclerosus: ongoing dermal fibrosis produces labial resorption, midline fusion, clitoral phimosis, and introital stenosis; signalled by dyspareunia, splitting/fissuring with intercourse, or obstructed voiding. Scarring is irreversible even after steroid therapy.
• Malignant transformation: a fixed, indurated, ulcerated, or hyperkeratotic plaque that fails to respond to potent topical steroid signals differentiated VIN or keratinizing squamous cell carcinoma — biopsy, do not re-treat.
• Steroid-related local toxicity: epidermal atrophy, telangiectasia, striae, rebound dermatitis, and secondary candidiasis from prolonged ultrapotent corticosteroid use.

Infectious complications

• Bartholin abscess extension: spreading erythema and cellulitis; necrotizing fasciitis with pain out of proportion, crepitus, dusky skin, and systemic toxicity is a surgical emergency requiring debridement and broad-spectrum antibiotics, particularly in diabetics.
• Neonatal HSV: intrapartum transmission from active genital lesions causes disseminated or CNS disease with high mortality — an obstetric emergency; ACOG recommends cesarean delivery for active lesions or prodrome at labor and antiviral suppression in late pregnancy.
• HSV sacral radiculopathy (Elsberg syndrome): urinary retention and perineal anesthesia during primary infection.
• Bacterial vaginosis and trichomoniasis are associated with preterm birth, PROM, post-procedural pelvic infection, and increased HIV acquisition through mucosal inflammation.

Complications of oncologic treatment

• Chronic lower-extremity lymphedema and lymphocyst after inguinofemoral lymphadenectomy — the principal reason sentinel node biopsy is preferred.
• Groin wound breakdown and infection after radical vulvectomy, from tension and compromised perfusion in a contaminated field; heralded by serous drainage and dehiscence.
• Radiation sequelae: vaginal stenosis and mucosal atrophy causing dyspareunia; rectovaginal or vesicovaginal fistula presenting as continuous fecal or urinary leakage per vagina — requires urgent evaluation and exclusion of recurrent tumor.
• Hemorrhage from an ulcerated exophytic tumor and urosepsis from obstruction are emergent presentations of advanced disease.
• Vulvar melanoma disseminates hematogenously early; thick lesions at diagnosis drive the poor survival.

• Lichen sclerosus buzzwords: porcelain-white, parchment-thin ("cigarette-paper") plaques in a figure-of-eight distribution around vulva and anus, most often postmenopausal. Treatment is clobetasol, and the single best next step for any thickened, ulcerated, or steroid-refractory area is punch biopsy.
• The common distractor is lichen simplex chronicus: thickened, leathery, hyperpigmented skin from chronic scratching, with no malignant potential — contrast with lichen sclerosus, which carries a small but real risk of squamous cell carcinoma.
• Two pathways to vulvar SCC: HPV-driven basaloid/warty disease in younger women (p16 block-positive) versus dVIN arising in lichen sclerosus in older women (p53-abnormal, keratinizing). Squamous cell carcinoma is the most common vulvar malignancy overall.
• The DES association examiners love: in-utero diethylstilbestrol exposure → clear cell adenocarcinoma of the upper anterior vagina, with vaginal adenosis (persistent müllerian columnar epithelium) as the precursor, plus T-shaped uterus and cervical hood. This is a non-HPV pathway.
• Sarcoma botryoides: embryonal rhabdomyosarcoma presenting as a grape-like polypoid mass protruding from the vagina of a girl under age 5; desmin and myogenin positive.
• Extramammary Paget disease of the vulva: pruritic, erythematous, eczematous weeping plaque that fails topical steroids; large pale intraepidermal cells that are PAS-positive and CK7-positive but S100-negative — the distractor is melanoma, which is S100/HMB-45 positive.
• Bartholin gland mass over ~40 or one that recurs after drainage: excisional biopsy to exclude adenocarcinoma, not repeat incision and drainage.
• Bedside discriminators: clue cells with pH >4.5 and positive whiff test = bacterial vaginosis; pseudohyphae with normal pH = candidiasis; motile flagellates with strawberry cervix = trichomoniasis (treat the partner). Most vaginal malignancy is metastatic — usually from cervix or endometrium — before assuming a primary vaginal cancer.