What is the most common type of cancer that appears on the mons pubis?

Most Common Cancer of the Mons Pubis

Squamous cell carcinoma (SCC) is the most common type of cancer that appears on the mons pubis, with HPV-associated subtypes being particularly prevalent in this region.

Epidemiology and Risk Factors

Cancers of the genital region, including the mons pubis, are relatively rare but have distinct epidemiological patterns:

• Human papillomavirus (HPV) infection is the primary risk factor, present in 80-85% of anogenital cancers 1
• Other risk factors include:
  • Immune suppression (HIV infection, transplant recipients, long-term immunosuppressant use)
  • Smoking history
  • History of other HPV-related cancers
  • Chronic inflammation
  • Poor hygiene
  • Advanced age

Histological Types

The most common cancers affecting the mons pubis include:

1. Squamous Cell Carcinoma (SCC) - by far the most common type:

   • HPV-associated subtypes:
     • Basaloid (4-10% of cases) 1
     • Warty (5-10% of cases) 1
     • Clear cell (less than 1% of cases) 1
   • HPV-independent subtypes:
     • Usual type (45-75% of cases) 1
     • Verrucous (3-8% of cases) 1
     • Papillary (2-15% of cases) 1

2. Less common types:

   • Keratoacanthoma 2
   • Basal cell carcinoma
   • Melanoma
   • Adenocarcinoma

Clinical Presentation

Cancers of the mons pubis typically present as:

• Raised or ulcerated lesions
• Persistent non-healing wounds
• Bleeding or discharge
• Pruritus or pain
• Palpable mass

Diagnostic Approach

When a suspicious lesion is found on the mons pubis:

1. Physical examination - document morphological and physical characteristics of the lesion
2. Biopsy - histological confirmation is mandatory as various histologies are possible 1
3. Regional lymph node assessment - physical examination of both groins, recording characteristics of nodes 1
4. HPV testing/p16 immunohistochemistry - to determine HPV association 1
5. Imaging - for staging if malignancy is confirmed:
   • CT scan of thorax, abdomen, and pelvis
   • MRI for local staging
   • PET-CT for detection of metastases in node-positive disease 1

Prognostic Factors

The most important prognostic factors include:

• Lymph node status - the single most important prognostic factor 3
• Histological subtype - basaloid and sarcomatoid variants have worse prognosis 1
• Depth of invasion - deeper invasion correlates with higher risk of nodal metastasis
• Tumor size - larger tumors have worse prognosis
• HPV status - HPV-positive tumors may have better survival outcomes 1

Treatment Considerations

Treatment depends on the stage and extent of disease:

• Localized disease:

  • Surgical excision with appropriate margins
  • Consideration of sentinel lymph node biopsy for tumors >2cm 3

• Regional disease:

  • Lymph node dissection for confirmed nodal metastases
  • Adjuvant radiation therapy for high-risk features

• Advanced disease:

  • Combined modality therapy with chemoradiation
  • Systemic therapy for metastatic disease

Clinical Pearls and Pitfalls

• Don't miss precursor lesions: Intraepithelial neoplasia can precede invasive cancer and should be treated appropriately
• Consider HPV vaccination: Prophylactic HPV vaccination can prevent up to 80% of anogenital cancers 1
• Beware of misdiagnosis: Some benign conditions like keratoacanthoma can mimic SCC but have different management approaches 2
• Monitor for synchronous lesions: Patients with HPV-related vulvar cancer often have synchronous or metachronous HPV-related lesions elsewhere in the anogenital region 1
• Don't neglect lymph node assessment: Even with small primary tumors, lymph node status remains the most important prognostic factor 3