Invasive Penile Squamous Cell Carcinoma

Comment

Prevalence
Penile cancer is rare in industrialized countries. Early detection is a critical factor for both overall survival and organ function. If successful interventions are to be made, physicians should be familiar with known risk factors as well as unusual presentations, such as lesions presenting in young circumcised men, as reported above. Similarly, tumors located on the shaft of the penis represent an uncommon location for tumor presentation, occurring in less than 5% of PSCC cases.⁸ Penile SCC most commonly develops as a solitary painless lesion on the glans, balanopreputial sulcus and/or prepuce.⁹ In our case, histopathology confirmed high-grade invasive SCC arising from squamous cell carcinoma in situ, an entity generally associated with older men with a 10% to 20% rate of progression into invasive SCC.⁹ Our patient denied any clinical change in the appearance of the tumor in the years prior to the current presentation, making it possible that the condyloma treated 8 years prior was squamous cell carcinoma in situ or PSCC. As many as 25% of premalignant lesions are mistaken for benign lesions, which can thus delay treatment and allow progression to malignancy.¹⁰

Diagnosis
Penile SCC often is etiologically subcategorized into 2 pathways based on HPV dependence or independence. Recent research suggests that this distinction often is difficult to make, and accurate laboratory and pathologic confirmation of HPV DNA, intact virions, and viral-related cutaneous changes is not always possible, leading to much speculation regarding the exact role of HPV in tumorigenesis.¹¹ Cancers developing in the absence of HPV DNA often occur secondary to chronic inflammatory conditions such as lichen planus or lichen sclerosus. Human papillomavirus DNA has shown to be present in 70% to 100% of all SCC in situ of the penis¹¹; therefore, the transformation of in situ disease to an invasive tumor in our patient most likely occurred via an HPV-dependent pathway. Viral carcinogenesis in the HPV-dependent pathway involves inactivation of host cell cycle regulatory proteins, specifically the retinoblastoma and p53 regulatory proteins by the viral oncoproteins E7 and E6, respectively.^12,13 Human papillomavirus–dependent pathways are related to a patient’s age at first sexual intercourse, number of sexual partners, and history of condyloma and other sexually transmitted diseases.^14,15 High-risk HPV types 16 and 18 are the most common viral types found in HPV related premalignant lesions, making it possible to decrease the incidence of PSCC with recently developed vaccines.¹⁶ Human papillomavirus vaccines have been shown to reduce the incidence of anal intraepithelial neoplasias and genital warts in men.¹⁷ While the effects of the HPV vaccine on reducing PSCC could not be assessed in the study due to low incidence of disease (both in the study population and in general), it is thought that HPV vaccination could potentially decrease the incidence of all PSCCs by one third, making it an important resource in the primary prevention of the disease.¹⁸

Management
Contemporary surgical management of PSCC has evolved from organ resection in toto for all PSCCs to a more conservative approach based upon tumor stage and grade. The standard margin for surgical resection of PSCC is 2 cm, a procedure often referred to as a partial penectomy. This remains the most common procedure for surgical resection of PSCC and has achieved good local control, with reported recurrence rates of 4% to 8%.^19,20 Complication rates of the procedure are moderate one-third of patients experiencing compromise of sexual activity after surgery.²¹ With evidence that smaller resection margins may result in good local control and a lower incidence of postoperative functional impairment, resection margins of 5, 10, and 15 mm have been advocated for PSCCs of varying histologic grades and tumor stages.^22-24 Treatment options for T1 and in situ tumors have expanded to include glansectomy, margin-controlled Mohs micrographic surgery, and ablative laser therapy for local disease control.^5,20 More advanced tumors are still treated with partial or complete penectomy given the high risks for locoregional recurrence and distant spread.

Prognosis
The most important factor predicting survival in patients with PSCC is metastasis to inguinal lymph nodes. The 5-year survival rate for patients without nodal involvement is 85% to 100%, while those with pathologically positive lymph nodes have a 5-year survival rate of 15% to 45%.²⁵ Once distant metastasis occurs, the mean time of survival is 7 to 10 months.²⁶ Our patient presented with high-grade PSCC with histologic lymphovascular spread and palpable inguinal lymph nodes. When stratified with other similar cases at presentation, our patient was at a considerable risk for locoregional as well as distant metastasis. Management with regional nodal dissection with a plan for close observation (and deferment of chemotherapeutics) was based upon evaluations from multiple different medical specialties.

Conclusion

Invasive PSCC is rare in young circumcised adults, and a delay in diagnosis can lead to considerable morbidity and mortality. We present a case of invasive PSCC arising in the setting of squamous cell carcinoma in situ in an area previously treated with cryotherapy and imiquimod. Our patient’s young age, concurrent hepatitis C infection, and contralateral locoregional nodal metastasis made this a complex case, involving evaluation and treatment by multiple medical disciplines. This case highlights the importance of biopsy in any lesion recalcitrant to conventional modalities regardless of the patient’s age. Early detection and treatment of PSCC can prevent organ dysfunction, loss of organ, and even death.