Monday 9 July 2012
Bowen’s disease; cutaneous squamous cell carcinoma in situ; cutaneous epidermoid carcinoma in situ. Ep. John T. Bowen
Definition: Bowen’s disease (also known as "squamous cell carcinoma in situ") is a neoplastic skin disease. Bowen’s disease can be considered as an early stage or intraepidermal form of cutaneous squamous cell carcinoma.
Bowen’s disease typically presents as a gradually enlarging, well demarcated erythematous plaque with an irregular border and surface crusting or scaling. This is a persistent progressive non-elevated red scaly or crusted plaque which is due to an intraepidermal carcinoma and is potentially malignant.
BD may occur at any age in adults but is rare before the age of 30 years - most patients are aged over 60. BD occurs predominantly in women (70-85% of cases).
Any site may be affected, although involvement of palms or soles is uncommon.
About 60-85% of patients have lesions on the lower leg, usually in previously or presently sun exposed areas of skin. The lesions may occur anywhere on the skin surface or on mucosal surfaces.
Bowen’s disease is essentially equivalent to squamous cell carcinoma in situ.
Atypical squamous cells proliferate through the whole thickness of the epidermis. The entire tumor is confined to the epidermis and does not invade into the dermis (squamous cell carcinoma "in situ"). The cells in Bowen’s are often highly atypical under the microscope, and may in fact look more unusual than the cells of some invasive squamous cell carcinomas.
Bowen’s disease is a form of carcinoma in situ, and accordingly shows full-thickness involvement of the epidermis, and sometimes the pilosebaceous epithelium, by atypical keratinocytes.
This is associated with disorderly maturation of the epidermis, mitoses at different levels, multinucleate keratinocytes, and dyskeratotic cells. Usually there is loss of the granular layer, with overlying parakeratosis and sometimes hyperkeratosis.
Several histological variants have been described, and more than one of these patterns may be present in different areas of the same lesion.
- In the psoriasiform pattern there is regular acanthosis with thickening of the rete ridges and overlying parakeratosis.
- In the atrophic form there is thinning of the epidermis, which shows full-thickness atypia and disorganization. There is usually overlying hyperkeratosis and parakeratosis.
- The verrucous-hyperkeratotic type is characterized by hyperkeratosis, papillomatosis, and sometimes intervening pit-like invaginations.
- The papillated variant, which has sometimes been included with the verrucous-hyperkeratotic type, is an exophytic/endophytic, sometimes keratotic lesion.
- A perinuclear halo is present in some of the cells suggestive of koilocytosis.
- The irregular variant shows irregular acanthosis, and often extensive chronic inflammation in the underlying dermis.
- In the pigmented type there is melanin in individual tumor cells and melanophages in the underlying dermis.
- The pagetoid variant has nests of cells with pale cytoplasm and thin strands of relatively normal keratinocytes intervening; the basal layer may also be spared. Sometimes this is associated with psoriasiform hyperplasia of the epidermis.
mucinous and sebaceous metaplasia
- Mucinous and sebaceous metaplasia characterize two other rare histological patterns.
clear cell change
- Clear cell change represents outer root sheath differentiation.
- HPV types have been identified in this clear cell variant.
Erythroplasia of Queyrat
- Erythroplasia of Queyrat is a form of squamous cell carcinoma in situ arising on the glans or prepuce, possibly induced by HPV.
actinic keratosis (solar keratosis)
- Bowen’s disease differs from actinic (solar) keratosis in the full-thickness atypia of the epithelium and in usually sparing the acrosyringium and sometimes also the basal layer which is always atypical in actinic keratoses.
- Both lesions may show aneuploidy of the constituent cells, and both may express mutant p53 protein and p21.
- In solar keratoses the keratin and involucrin distribution is similar to normal epidermis, whereas in Bowen’s disease the keratin distribution is variable.
- In arsenical keratoses, in-situ carcinoma indistinguishable from Bowen disease may develop.
- Pagetoid dyskeratosis differs from Bowen disease by the presence of scattered pale cells with small pyknotic nuclei in a background of otherwise normal skin.
Attempts have been made to introduce a three-tiered grading system for keratinocytic atypia, similar to the previous system of grading atypia on the vulva and cervix. In an informal trial, dermatopathologists were reliably able to categorize the continuum of keratinocytic atypia with substantial concordance.
Keratinocytic intraepithelial neoplasia (KIN) has not yet received much acceptance in the broader community of pathologists and dermatologists. The concept is not supported by experimental work involving cyclin A levels in actinic keratosis and Bowen’s disease.
Freezing, cauterization or diathermy coagulation is often effective treatment.
Photodynamic therapy (PDT), Cryotherapy (freezing) or local chemotherapy (with 5-fluorouracil) are favored by some clinicians over excision.
Because the cells of Bowen’s disease have not invaded the dermis, it has a much better prognosis than invasive squamous cell carcinoma.
Outstanding results have been noted with the use of imiquimod for Bowen’s disease of the skin, including the penis (erythroplasia of Queyrat), although Imiquimod is not FDA approved for the treatment of squamous cell carcinoma.
cutaneous epiderdmoid carcinoma