A 42-year-old shepherd from Himachal Pradesh presents with a 2-year history of progressive right upper quadrant pain and a palpable mass. Ultrasound reveals a large cystic lesion in the liver with internal septations and 'daughter cysts'. Serum IgG against Echinococcus granulosus is positive. CT chest shows no pulmonary involvement. What is the most appropriate next step in management?

Explanation

## Clinical Scenario: Hepatic Echinococcosis This patient has **symptomatic hepatic cystic echinococcosis** (hydatid disease) caused by *Echinococcus granulosus*. The presence of daughter cysts on imaging is pathognomonic for this infection. The shepherd's occupational exposure (contact with infected dogs) and endemic geography (Himalayas) are typical risk factors. ## Management Algorithm for Hepatic Echinococcosis ```mermaid flowchart TD A[Hepatic echinococcosis diagnosed]:::outcome --> B{Cyst characteristics?}:::decision B -->|Small, inactive| C[Observation with serial imaging]:::action B -->|Large, symptomatic, uncomplicated| D{Suitable for PAIR?}:::decision D -->|Yes| E[PAIR + albendazole]:::action D -->|No| F[Surgical excision]:::action B -->|Complicated/ruptured| G[Surgical intervention]:::action E --> H[Monitor response at 3-6 months]:::action F --> I[Pericystectomy or partial cystectomy]:::action ``` ## Why PAIR Is the Best Choice Here **Key Point:** **PAIR** (Percutaneous Aspiration, Injection, Re-aspiration) is now the **first-line percutaneous intervention** for uncomplicated hepatic echinococcosis, especially for cysts 5–15 cm in diameter with daughter cysts. **High-Yield:** PAIR advantages: - Minimally invasive; lower morbidity than open surgery - Can be performed under ultrasound or CT guidance - Sclerosant (hypertonic saline, ethanol, or albendazole) kills protoscolices - Requires **concurrent albendazole** (10–15 mg/kg/day for ≥4 weeks before and after) - Success rate: 80–90% for uncomplicated cysts - Suitable for this patient: large, symptomatic, with daughter cysts, no pulmonary involvement ## Cyst Classification (WHO-IWGE) | Type | Imaging | Viability | Management | |------|---------|-----------|-------------| | **CL** | Cystic lesion (no daughter cysts) | Inactive | Observation | | **CE1** | Unilocular, anechoic | Active | PAIR or surgery | | **CE2** | Multilocular, daughter cysts | Active | **PAIR or surgery** | | **CE3** | Daughter cysts + degenerating wall | Transitional | PAIR or surgery | | **CE4** | Heterogeneous, no daughter cysts | Inactive | Observation | | **CE5** | Calcified rim | Dead | Observation | This patient has **CE2** (daughter cysts visible)—ideal for PAIR. ## Why Not the Other Options? **Immediate Surgery:** While surgical excision (pericystectomy) is effective, it carries higher morbidity (bile leak, infection, anaphylaxis if cyst ruptures) and longer hospital stay. PAIR is preferred as first-line for uncomplicated cysts suitable for percutaneous access. **Albendazole Monotherapy:** Chemotherapy alone is **not curative** for large cysts. It may prevent growth or cause partial involution but cannot reliably eliminate established cysts. It is used as **adjunctive therapy** (before/after PAIR or surgery) or for inoperable/disseminated disease. **Observation Alone:** The cyst is **symptomatic** (RUQ pain, palpable mass) and **large** (daughter cysts visible). Observation is reserved for small, incidental, inactive cysts (CE4, CE5). Active symptomatic cysts require intervention. **Clinical Pearl:** The presence of daughter cysts indicates an **active, proliferating cyst**. These require intervention; observation risks cyst growth, rupture, and anaphylactic shock. **Mnemonic: PAIR PROTOCOL** - **P**ercutaneous access under imaging - **A**spiration of cyst fluid (diagnostic + therapeutic) - **I**njection of sclerosant (kills protoscolices) - **R**e-aspiration to remove dead material - **Plus albendazole cover** (4 weeks before, 4 weeks after)