Differential Diagnoses for a New Vulvar Lump
A new vulvar lump requires immediate biopsy of any suspicious lesion to exclude malignancy, particularly vulvar squamous cell carcinoma, which accounts for 90% of vulvar cancers and presents most commonly as a mass on the labia majora. 1, 2
Malignant Differentials (Must Exclude First)
Vulvar Squamous Cell Carcinoma
- Most common malignant vulvar tumor (90% of cases), typically presents as a single mass or ulcer on the labia majora or minora in HPV-negative tumors. 1, 2
- HPV-positive tumors more commonly show multifocal lesions and concurrent cervical neoplasia. 1, 2
- Associated symptoms include pruritus, pain/irritation, vulvar bleeding or discharge, though many cases are asymptomatic. 1, 2
- Risk factors: HPV infection (particularly types 16 and 18), increasing age (median 65-70 years), cigarette smoking, chronic vulvar inflammation, and immunodeficiency. 1, 2
- Diagnosis requires punch biopsy of all suspicious lesions, including underlying stroma while avoiding necrotic areas. 1
Other Malignant Histologies (Rare)
- Melanoma, extramammary Paget disease, Bartholin gland adenocarcinoma, verrucous carcinoma, basal cell carcinoma, and sarcoma collectively account for 10% of vulvar cancers. 1
Benign Differentials
Bartholin Gland Cyst or Abscess
- Most common benign cystic vulvar lesion, typically located in the posterolateral aspect of the vestibule. 3, 4
- Presents as a unilateral, fluctuant mass that may be painful if infected (abscess). 3, 4
- Special attention required for cysts in women >40 years, as Bartholin gland adenocarcinoma must be excluded. 3
Epidermoid Inclusion Cysts
- Common benign cystic lesions resulting from epithelial implantation following trauma or episiotomy. 3, 4
- Typically asymptomatic unless secondarily infected. 3, 4
Lipoma
- Rare benign soft tissue tumor presenting as a soft, pasty, mobile mass under the skin. 5
- Imaging (MRI) shows homogenous hyperintense mass with marked signal decrease on fat-suppressed sequences. 5
- Must be differentiated from liposarcoma through histopathological evaluation of excised tissue. 5
Leiomyoma
- Exceptionally rare (0.03% of all gynecological tumors), presents as a solid, unilateral mass, most commonly on the labia majora. 6
- Can occur in adolescents and young women. 6
- Ultrasonography reveals a solid mass with superficial vascularity. 6
- Often misdiagnosed as Bartholin cyst; differential includes sarcoma, lipoma, and fibroid. 6
Angiomas
- Benign vascular tumors that are typically asymptomatic. 4
Critical Diagnostic Approach
Immediate Evaluation Required
- Comprehensive examination of vulva, vagina, and cervix with cytologic smears, given the multifocal nature of squamous cell intraepithelial neoplasia. 1, 2
- Biopsy is mandatory for any suspicious lesion to exclude invasion. 1, 2
- Document lesion size, location relative to midline, relationship to adjacent organs (urethra, vagina, anus), and presence of multifocal disease. 1
- Clinical palpation of groin lymph nodes, though limited by high false-negative rate. 1
Imaging Considerations
- Transvaginal ultrasound or MRI for characterization of cystic versus solid lesions when surgical management is considered. 3
- CT, PET/CT, or MRI may be used to delineate tumor extent if malignancy is suspected. 1
Red Flags Requiring Urgent Malignancy Workup
- Fixed lesions, those associated with pain or bleeding, or occurring in women >40 years warrant heightened suspicion. 3
- Ulcerated lesions, rapid growth, or concurrent symptoms of pruritus/pain. 1, 2
- Multifocal lesions in HPV-positive patients. 1, 2
Management Pitfalls to Avoid
- Never assume a vulvar mass is benign without histopathological confirmation, as clinical and imaging profiles of benign and malignant lesions overlap significantly. 5
- Do not delay biopsy in symptomatic patients or those with suspicious features. 1, 2
- Bartholin cysts in women >40 years require excision and pathological evaluation to exclude adenocarcinoma. 3