A 42-year-old woman from rural Maharashtra presents to the emergency department with a 3-day history of severe abdominal pain, profuse watery diarrhea, and vomiting. Her husband reports she consumed water from a hand pump near an old pesticide storage site. On examination, she is hypotensive (BP 80/50), tachycardic (HR 118/min), and has signs of severe dehydration. Her skin shows diffuse hyperpigmentation and hyperkeratosis on the palms and soles. Laboratory investigations reveal: hemoglobin 16 g/dL, WBC 12,000/μL, serum creatinine 2.8 mg/dL, and elevated liver enzymes. Urine shows dark brown discoloration. What is the most likely diagnosis?

Explanation

## Clinical Presentation Analysis **Key Point:** The combination of acute gastrointestinal symptoms (severe diarrhea, vomiting, abdominal pain) with chronic skin manifestations (hyperpigmentation and hyperkeratosis) is pathognomonic for arsenic poisoning with mixed acute and chronic exposure. ## Diagnostic Features in This Case ### Acute Arsenic Toxicity - Profuse "rice-water" diarrhea (cholera-like) - Severe abdominal pain and vomiting - Cardiovascular collapse (hypotension, tachycardia) - Acute renal injury (elevated creatinine) - Dark urine (myoglobinuria or hemoglobinuria) ### Chronic Arsenic Exposure Indicators - **Hyperpigmentation** of skin (diffuse, especially on trunk and flexures) - **Hyperkeratosis** on palms and soles (pathognomonic) - Mees' lines on nails (horizontal white lines) **High-Yield:** The presence of BOTH acute GI symptoms AND chronic skin changes (hyperkeratosis + hyperpigmentation) strongly suggests arsenic as the culprit. This dual presentation is rare with other heavy metals. ## Mechanism of Arsenic Toxicity 1. **Acute phase:** Inhibits cellular respiration via sulfhydryl group binding → multi-organ dysfunction 2. **Chronic phase:** Accumulates in skin, hair, nails → keratin precipitation → hyperkeratosis 3. **Carcinogenic:** Increases risk of skin, lung, and GI malignancies ## Laboratory Findings | Finding | Explanation | | --- | --- | | Hemoconcentration (Hb 16 g/dL) | Severe fluid loss from diarrhea | | Elevated creatinine | Acute tubular necrosis from arsenic | | Dark urine | Myoglobin or hemoglobin from tissue damage | | Leukocytosis | Stress response | **Clinical Pearl:** Arsenic is absorbed from the GI tract and excreted in urine within 24–48 hours. Urine arsenic levels >50 μg/L (normal <10 μg/L) confirm acute exposure. Hair and nail analysis detect chronic exposure. **Tip:** The rural setting and hand pump near pesticide storage is a classic epidemiological clue for arsenic contamination in groundwater — a known public health hazard in parts of India (West Bengal, Assam, Punjab). ## Management Priorities 1. **Supportive care:** Aggressive IV fluid resuscitation (isotonic saline) 2. **Electrolyte correction:** Monitor K^+^, Na^+^, Mg^2+^ 3. **Chelation therapy:** Dimercaprol (BAL) or DMSA (succimer) for symptomatic acute poisoning 4. **Monitoring:** Serial ECG (QT prolongation, arrhythmias), renal function, cardiac output [cite:Parikh Textbook of Forensic Medicine Ch 15]