Predictors of Concomitant Pulmonary Involvement in Hepatic Cystic Echinococcosis: A Clinical Risk Stratification Model

Acta Parasitologica (2026) 71:98 https://doi.org/10.1007/s11686-026-01291-4 ORIGINAL ARTICLE Predictors of Concomitant Pulmonary Involvement in Hepatic Cystic Echinococcosis: A Clinical Risk Stratification Model Oğuzhan Taş1 · Mehmet Ali Eryazğan2 Received: 3 February 2026 / Accepted: 13 April 2026 © The Author(s) 2026 Abstract Purpose Hepatopulmonary hydatidosis (HPH) is a clinically relevant presentation of hepatic cystic echinococcosis (CE) in which pulmonary involvement is present at the time of diagnosis. Reliable identification of patients at risk remains challenging, and indiscriminate thoracic imaging may lead to unnecessary investigations. This study aimed to identify hepatic predictors associated with concomitant pulmonary involvement and to develop a simple risk stratification model to support selective thoracic imaging. Methods We conducted a retrospective cohort study of patients with confirmed hepatic CE followed at a single tertiary center. Cyst activity was classified according to the World Health Organization (WHO) staging system, and anatomical distribution was assessed using a segment-based classification. Multivariable logistic regression was performed to identify predictors of HPH. A point-based clinical risk score (HepatoMAP) was derived by combining cyst activity and anatomical distribution. Model discrimination and calibration were assessed using receiver operating characteristic (ROC) analysis, bootstrap validation, and calibration plots. Results Among 292 patients, 23 (7.8%) had hepatopulmonary hydatidosis (HPH) at initial diagnosis. Active cysts (WHO CE1–2) were strongly associated with HPH (91.3% in HPH vs. 33.2% in hepatic-only disease, p < 0.001) and remained the only independent predictor in multivariable analysis. The HepatoMAP score demonstrated good discrimination (AUC 0.83) with good calibration (bootstrap-corrected slope 0.97). No cases of HPH were observed in patients with low-risk scores (0–1 points), whereas HPH occurred predominantly in patients with scores ≥ 3. Conclusion In hepatic CE, concomitant pulmonary involvement at baseline was strongly associated with cyst activity and showed a structured but non-independent relationship with segmental topography. The HepatoMAP score showed promising rule-out characteristics in this cohort and may support more selective use of thoracic imaging. Prospective external validation is required before routine clinical implementation. Keywords Cystic echinococcosis · Hepatopulmonary hydatidosis · Segmental liver anatomy, · WHO cyst classification · Risk stratification Introduction Oğuzhan Taş 1 Department of General Surgery, Faculty of Medicine, Aksaray Training and Research Hospital, Aksaray University, Aksaray, Turkey 2 Department of Thoracic Surgery, Faculty of Medicine, Aksaray Training and Research Hospital, Aksaray University, Aksaray, Turkey Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the larval stage of Echinococcus granulosus and remains a significant public health problem in endemic regions worldwide [1–3]. The liver and lungs represent the two most commonly involved organs, reflecting both portal venous filtration and systemic dissemination pathways [4]. Although hepatic involvement predominates, pulmonary disease may occur either concurrently or secondarily, leading to hepatopulmonary hydatidosis (HPH), a clinically relevant manifestation associated with increased diagnostic complexity, therapeutic challenges, and prolonged 13 98 Page 2 of 11 follow-up [5–7]. Reported frequencies of pulmonary involvement among patients with hepatic CE vary widely, largely owing to heterogeneity in study populations, imaging strategies, and duration of surveillance [8]. The biological behavior of CE is heterogeneous and influenced by cyst viability, host-related factors, and anatomical conditions. The development of HPH is generally attributed to a combination of hematogenous dissemination and transdiaphragmatic spread, although the relative contribution of these mechanisms remains incompletely defined [9]. Viable cysts may exhibit higher intracystic pressure, increased permeability, and a greater propensity for rupture or systemic spread compared with inactive or degenerative lesions. In routine clinical practice, cyst biological activity is most commonly assessed using the World Health Organization Informal Working Group on Echinococcosis (WHO-IWGE) classification, which stratifies cysts into active (CE1–CE2), transitional (CE3), and inactive (CE4–CE5) stages [2, 10]. However, cyst activity alone does not adequately explain why pulmonary involvement develops in only a subset of patients with hepatic CE, indicating that additional modifiers of dissemination risk are likely involved. Hepatic anatomical distribution and cyst burden have long been recognized as potential determinants of disease behavior in CE, particularly with respect to complications and extrahepatic spread [4]. Beyond hydatid disease, segmental liver anatomy has been shown to influence disease distribution and clinical outcomes in a variety of hepatic conditions, underscoring the biological plausibility of anatomical modifiers [11, 12]. Segment-based assessments may capture clinically relevant information by reflecting cyst proximity to vascular structures, diaphragmatic surfaces, and hepatic venous outflow, all of which could plausibly influence the likelihood of thoracic involvement. From an infectious disease perspective, anatomical factors may therefore interact with cyst viability to shape dissemination patterns rather than acting as isolated determinants. In the absence of reliable predictors for HPH, thoracic imaging is often applied liberally in patients with hepatic CE, particularly in endemic settings such as Türkiye, where disease burden remains substantial [13, 14]. Although thoracic computed tomography is highly sensitive for detecting pulmonary hydatid disease, routine imaging of all patients with hepatic CE may result in unnecessary radiation exposure, increased healthcare costs, and incidental findings of uncertain clinical relevance [7, 8]. A pragmatic, clinically applicable risk stratification approach capable of identifying patients at negligible risk for HPH could therefore support more selective imaging strategies without compromising patient safety. Against this background, we aimed to identify hepatic features associated with hepatopulmonary hydatidosis in 13 Acta Parasitologica (2026) 71:98 patients with hepatic cystic echinococcosis and to develop a simple, clinically applicable risk stratification model. By integrating cyst biological activity with hepatic anatomical distribution, our objective was to explore whether these features could support estimation of baseline HPH risk and to guide the selective use of thoracic imaging in routine clinical practice. Materials and Methods Study Design and Population This single-center retrospective study included patients (...truncated)