Intraepithelial carcinoma (Bowen disease)https://en.wikipedia.org/wiki/Squamous_cell_skin_cancer
Intraepithelial carcinoma (Bowen disease) shows 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. This disease is technically classified as cancerous, but non-invasive unlike common cancers. (i.e. it is a cancer with a good prognosis.)

It usually appears as a erythematous, scaly or crusty area anywhere on the body. The most common location is lower legs.

It is curable by various treatment options such as cryotherapy, curettage, cautery, photodynamic therapy, or excision of the lesion.

○ Diagnosis and Treatment
#Dermoscopy
#Skin biopsy
#Mohs surgery
#Photodynamic therapy
  • Typical case ― Intraepithelial carcinoma (Bowen disease) may be misdiagnosed as a long-lasting, non-itchy eczema.
  • Cutaneous horn ― Unlike warts, it presents as a hard nodule, and a biopsy is necessary to exclude malignancy.
  • If a wound persists for a prolonged period, skin cancer should be considered.
  • Intraepithelial carcinoma (Bowen disease) ― Typical case
  • In this case, Irritated seborrheic keratosismay also be considered as a potential differential diagnosis.
  • It is often mistaken for an allergic disorder (for example, nummular eczema ).
  • Intraepithelial carcinoma (Bowen disease) ― Typical case
  • Another typical case presents similar morphological features to allergic conditions.
References Bowen's Disease 35287414 
NIH
Bowen's disease (BD) is an in-situ squamous cell carcinoma of epidermis. The etiology of BD is multifactorial with high incidence among Caucasians. BD is common in photo-exposed areas of skin, but other sites can also be involved. Lesions are usually solitary. The morphology of BD differs based on age of the lesion, site of origin, and the degree of keratinization. BD is considered as the lull before the storm, which precedes an overt squamous cell carcinoma. Histopathology is the gold standard diagnostic modality to confirm the diagnosis.
 Bowen disease - Case reports 17001052 
NIH
Bowen disease is most commonly found in white patients over 60 years old. Other risk factors include chronic sun exposure, immunosuppression, arsenic exposure and cutaneous human papillomavirus (HPV) infection. HPV types 16, 18, 34 and 48 cause Bowen disease at genital sites; the role of HPV in nongenital cases of Bowen disease is less well defined. HPV types 2, 16, 34 and 35 have been rarely identified within nongenital lesions.