## Chronic Arsenic Poisoning: Cutaneous Manifestations ### Characteristic Skin Findings **Key Point:** Chronic arsenic exposure causes **Bowen's disease** — a squamous cell carcinoma in situ characterized by full-thickness dysplasia of the epidermis with hyperkeratosis. ### Histopathological Features of Bowen's Disease (Arsenic-Related) | Feature | Description | |---------|-------------| | **Dysplasia** | Full-thickness epidermal dysplasia with loss of maturation | | **Hyperkeratosis** | Thickened stratum corneum, often with parakeratosis | | **Cytologic atypia** | Irregular nuclei, increased mitotic activity, hyperchromatic cells | | **Intact basement membrane** | Distinguishes from invasive carcinoma | | **Location** | Non-sun-exposed areas (palms, soles, trunk) — typical of arsenic | ### Clinical Context **High-Yield:** Arsenic is a **Group 1 carcinogen**. Chronic exposure (>10 years) leads to: 1. Hyperpigmentation and hypopigmentation ("raindrop" pattern) 2. Hyperkeratosis of palms and soles 3. **Bowen's disease** → squamous cell carcinoma (5–10% progression) 4. Basal cell carcinoma and adenocarcinoma of internal organs **Clinical Pearl:** Bowen's disease from arsenic appears on **non-sun-exposed areas**, distinguishing it from solar keratosis (sun-exposed sites). ### Why Bowen's Disease? Bowen's disease is the **precancerous lesion of choice** for chronic arsenic toxicity because: - Arsenic binds to sulfhydryl groups in keratinocytes → mutagenesis - Causes p53 mutations → uncontrolled proliferation - Full-thickness dysplasia without basement membrane breach = carcinoma in situ [cite:Vij Forensic Medicine and Toxicology Ch 18]
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