HPV Type 6 Linked to Interdigital Squamous Cell Carcinoma Mimicking Toe Infection

A case report published in the medical journal Cureus has detailed a rare instance of squamous cell carcinoma (SCC) occurring between the toes of a 78-year-old farmer, a malignancy that was initially mistaken for a common skin infection.

The report highlights the diagnostic challenges associated with interdigital lesions, as the cancerous growth mimicked the appearance of a typical infection, delaying the initial diagnosis of the malignancy.

Medical researchers identified the presence of Human Papillomavirus (HPV) type 6 in the tumor, adding a layer of clinical complexity to the case given the typical behavior of that specific virus strain.

Clinical Presentation and Misdiagnosis

The patient, a 78-year-old male working as a farmer, presented with an ulcerative lesion located in the interdigital space of the toe. Because the location and appearance of the lesion were consistent with common foot ailments, it was initially treated as a localized infection.

In clinical practice, lesions between the toes are frequently attributed to tinea pedis (athlete’s foot) or bacterial infections, particularly in patients with occupational exposure to moisture and soil, such as farming. According to the report, the lesion’s failure to respond to standard antimicrobial treatments prompted further investigation.

A biopsy was eventually performed, which revealed that the tissue was not infected but was instead a squamous cell carcinoma. SCC is a type of skin cancer that develops in the squamous cells, which make up the middle and outer layers of the skin.

The Role of HPV Type 6

Following the diagnosis of SCC, researchers conducted polymerase chain reaction (PCR) testing to analyze the genetic material within the tumor. This testing confirmed the presence of HPV type 6.

The discovery of HPV type 6 is particularly noteworthy because the virus is generally classified as a low-risk HPV type. Unlike high-risk strains such as HPV 16 and 18, which are strongly linked to cervical and oropharyngeal cancers, HPV 6 is typically associated with benign growths, such as genital warts.

The presence of a low-risk HPV strain in a malignant squamous cell carcinoma of the toe is an unusual finding. The Cureus report explores whether the virus acted as a contributing factor to the oncogenesis or if its presence was incidental to the development of the cancer.

Understanding Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common form of skin cancer. While it most frequently appears on sun-exposed areas of the body—such as the face, ears, and hands—it can occur in non-sun-exposed regions, including the interdigital spaces of the feet.

When SCC occurs in areas not exposed to ultraviolet (UV) radiation, clinicians often look for other contributing factors. These can include:

• Chronic inflammation or long-term wounds.
• Exposure to certain chemicals or industrial agents.
• Viral infections, including various strains of HPV.
• Immunosuppression.

In the case of the 78-year-old farmer, the combination of age and potential occupational skin irritation may have played a role in the development of the lesion.

Diagnostic Implications for Healthcare Providers

The case serves as a clinical reminder of the importance of the differential diagnosis process. When a suspected infection does not resolve within the expected timeframe despite appropriate therapy, clinicians are encouraged to consider malignant possibilities.

The report emphasizes that interdigital SCC can be insidious because its location often hides the lesion from immediate view, and its appearance can closely resemble inflammatory or infectious processes.

Early detection remains critical for SCC, as the cancer can invade deeper tissues or metastasize to lymph nodes if left untreated. In this specific case, the identification of the malignancy allowed for the necessary surgical intervention to remove the tumor.

The detection of HPV type 6 in this patient contributes to the broader medical understanding of how different HPV strains interact with skin tissues in elderly populations and whether low-risk strains can occasionally be associated with malignant transformations under specific conditions.