Bowen Disease
Bowen disease (BD), also known as cutaneous squamous cell carcinoma in situ (cSCC in situ), is the next step on from precancerous keratinocyte lesions. At this stage, abnormal keratinocytes fill the entire thickness of the epidermis but have not yet broken through the basement membrane into the dermis.
In actinic keratosis (AK), the atypical cells are limited to the lower one-third to two-thirds of the epidermis; in Bowen disease, the atypia is full-thickness. An estimated 3–5% of Bowen lesions progress to invasive cSCC. Recognizing and fully treating the disease at this stage is key to minimizing the risk of microscopic invasion and spread.
At Haute-Derma, we follow a dedicated pathway for Bowen disease: accurate diagnosis with high-resolution dermoscopy and prompt biopsy, followed by a treatment plan that spares as much tissue as possible, prioritizes cosmetic outcome and can address wider areas of sun-damaged, precancerous skin.
Clinical Background and Pathology
Causes and Risk Factors
Actinic keratosis is driven mainly by UV light, but Bowen disease has a wider range of causes:
- Ultraviolet (UV) radiation: the leading cause on chronically sun-exposed skin (face, scalp, forearms).
- Chronic arsenic exposure: multiple Bowen patches on covered skin (trunk, palms, soles) point to past arsenic exposure from groundwater or unregulated traditional herbal remedies.
- Human papillomavirus (HPV): high-risk types (especially HPV-16, 18, 31 and 34) are closely linked to Bowen disease under and around the nails, on genital mucosa and in the anogenital region (including erythroplasia of Queyrat).
- Immunosuppression: organ transplant recipients, people on long-term immunosuppressants and people with HIV have a much higher risk and faster progression.
Clinical Features
- Appearance: a pink-red, pale gray or brown (pigmented) patch with a fairly well-defined but irregular, jagged edge. The surface is rough and scaly and may carry firmly stuck yellow or brown crusts; it is sometimes slightly raised or weeps a little.
- Location: 60–70% occur on exposed skin (head, face, neck, and the lower legs in women); the remaining 30% are on the trunk, palms, genital mucosa and around the nails.
- Special variants:
- Pigmented Bowen disease: a dark brown-black patch that is easily mistaken for melanoma in situ or pigmented basal cell carcinoma.
- Erythroplasia of Queyrat: Bowen disease of the foreskin or glans penis, seen as a deep red, smooth, velvety patch that bleeds easily and has a higher rate of progression to invasive cancer (10–30%).
Histopathology
- Full-thickness atypia: every layer of epidermal keratinocytes, from the basal to the spinous layer, is replaced by atypical cells with large, dark nuclei, abnormal mitoses and complete loss of polarity (the "windblown" appearance).
- Hyperkeratosis and parakeratosis: a thick stratum corneum with disorderly retained nuclei.
- Dyskeratosis: individual cells keratinize prematurely within the epidermis (cells with deeply eosinophilic cytoplasm).
- Intact basement membrane: the epidermis may thicken and push down into the upper dermis (psoriasiform hyperplasia), but the basement membrane remains continuous and no tumor cells breach into the dermis.
Differential Diagnosis and Immunohistochemistry (IHC)
| Condition | Distinguishing Microscopic Features and IHC Markers |
|---|---|
| Bowen disease (cSCC in situ) | Full-thickness epidermal atypia; intact basement membrane; diffuse p53 (+); Ki-67 (+) raised throughout the epidermis; p63 (+), p40 (+); BerEP4 (–). |
| Actinic keratosis (AK / KIN-1, KIN-2) | Atypia limited to the lower one-third or two-thirds of the epidermis; Ki-67 raised only in the lower layers; intact basement membrane. |
| Invasive squamous cell carcinoma (invasive cSCC) | Islands of atypical tumor cells breaching the basement membrane into the dermis; p63 (+); p40 (+); CK34betaE12 (+); BerEP4 (–). |
| Superficial basal cell carcinoma (superficial BCC) | Basaloid cell proliferation budding from the epidermis with peripheral palisading; BerEP4 (+); Bcl-2 (+); p40 (–/weak). |
| Extramammary Paget disease | Paget cells with pale cytoplasm, scattered singly or in nests within the epidermis; CK7 (+); CEA (+); CAM5.2 (+); p63 (–); p40 (–). |
| Melanoma in situ | Atypical melanocytes in nests or with pagetoid spread in the epidermis; SOX10 (+); Melan-A (+); S100 (+); p63 (–). |
Our Approach to Treating Bowen Disease
At Haute-Derma, we manage Bowen disease with a strong focus on fully controlling the lesion margins:
- Defining clinical and dermoscopic borders: unlike thin AK lesions, Bowen patches have clear visible edges, but the atypical cells often extend 2–5 mm beyond what can be seen with the naked eye.
- Balancing cure and cosmetic outcome: the treatment is chosen according to the site (face, around the eyes or nose, lower legs where wounds heal poorly, or the genital area).
- Watching for invasion: we always look for warning signs of invasive cancer (a firm lump, ulceration or bleeding, deep pain) and switch to surgical excision with safe margins if they appear.
How We Diagnose Bowen Disease at Haute-Derma
- High-resolution dermoscopy: we look for the classic dermoscopic signs of Bowen disease:
- Dotted or glomerular vessels arranged in rows or clusters.
- Fish-scale keratin or white-yellow surface scale.
- In the pigmented type: evenly spread brown-black globules or dots, or irregular pigment at the periphery.
- Diagnostic skin biopsy (punch or shave): every suspected Bowen lesion should be biopsied and sent for histopathology to confirm the diagnosis and rule out invasive squamous cell carcinoma before treatment.
- Systemic risk assessment: we ask about arsenic exposure, immune status and HPV history if the lesion is in the genital or nail area.
Specialist Treatment Options at Haute-Derma
Depending on the size, site and number of lesions, Haute-Derma offers a range of treatments:
- Surgical excision with safe margins:
- The gold standard for single, small to medium lesions on skin with good laxity.
- A surgical margin of 4–5 mm beyond the visible edge is recommended to remove as many microscopic tumor cells as possible.
- Mohs micrographic surgery:
- Preferred for Bowen lesions in sensitive areas (face, nose, ears, fingers, around the nails, genitals) and for recurrent lesions or those larger than 2 cm.
- The entire surgical margin is checked under the microscope during the procedure, so as much healthy tissue as possible is preserved.
- Photodynamic therapy (PDT):
- First choice for large Bowen patches, lesions on the lower legs of older adults (where surgical wounds heal poorly) and multiple lesions.
- A photosensitizer (5-ALA or MAL) is applied and left for 3 hours, then activated with a dedicated red light. Clearance rates are high (88–93%), with excellent cosmetic results and no contracted scars.
- Topical treatments (for patients who cannot have surgery):
- 5-fluorouracil (5-FU 5%): applied once or twice daily for 4–6 weeks, causing a strong inflammatory reaction that destroys the tumor.
- Imiquimod 5%: applied 3–5 times a week for 6–16 weeks, stimulating the body's own immune response to clear Bowen cells.
- Curettage and electrocautery / cryotherapy: used for small, superficial lesions on the trunk in older patients.
