Intra-Diaphragmatic Extralobar Pulmonary Sequestration |
| Intra-diaphragmatic
extralobar pulmonary sequestration (IDEPS) is among the rarest
congenital lung anomalies a surgeon will encounter. Pulmonary
sequestration as a whole accounts for less than 6.4 percent of all
congenital pulmonary malformations, and the extralobar subtype —
defined by its own visceral pleural covering, complete independence
from the normal lung, and systemic arterial supply — represents
only 14 to 25 percent of those. Of that fraction, the subset lodged
within the muscular layers of the diaphragm is rarer still: fewer than
one hundred pediatric cases have been documented in the world
literature since the condition was first formally described in the
early 1960s. Most surgeons will see only one or two cases in a career.
Yet the condition carries practical consequences that demand clear
surgical thinking, and familiarity with its behavior is not optional
for those who care for congenital lung malformations. The embryological basis of IDEPS follows the broader logic of extralobar sequestration. An accessory lung bud arising from the primitive foregut below the normal lung bud migrates caudally before proper pleural investment is established, deriving its blood supply from splanchnic vessels surrounding the foregut. When this anomalous tissue becomes entrapped within the diaphragmatic musculature rather than remaining supradiaphragmatic or descending into the retroperitoneum, the result is IDEPS. The lesion sits between the muscular layers of the diaphragm, predominantly on the left side — a laterality that is consistent across published series and appears to reflect the asymmetric architecture of diaphragmatic embryogenesis. It presents as a well-demarcated solid or mixed solid-cystic mass with a systemic feeding artery, most commonly arising from the sub-diaphragmatic abdominal aorta, and it has no connection to the tracheobronchial tree. The widespread adoption of prenatal ultrasonography has transformed the diagnostic moment for IDEPS. Virtually all contemporary cases are identified before birth, typically between 20 and 26 weeks of gestation, when a hyperechoic mass is detected in or near the diaphragm. Doppler interrogation can sometimes identify the aberrant feeding artery, which is a critical diagnostic clue. However, accurate prenatal localization of the lesion within the diaphragm rather than immediately above or below it is notoriously difficult, and most prenatal diagnoses simply classify it as extralobar sequestration without specifying the intra-diaphragmatic position. After birth, high-resolution angio-computed tomography is the cornerstone of preoperative planning. It defines the lesion's exact anatomical relationship to the diaphragmatic crura, identifies the feeding vessel and its origin, and allows the surgeon to anticipate which cavity — thoracic, abdominal, or both — will need to be entered. Angio-MRI may offer complementary soft-tissue characterization, and three-dimensional CT reconstruction has shown early promise in improving anatomical visualization before surgery. Despite all available imaging modalities, definitive intraoperative identification of the lesion as truly intra-diaphragmatic is sometimes achieved only after the abdomen or chest is opened. The case for surgical resection rests on several converging arguments, none of them trivial. Approximately 30 to 40 percent of resected IDEPS specimens demonstrate hybrid histology — that is, sequestration containing features of congenital pulmonary airway malformation (CPAM). This rate is somewhat higher than that observed in supradiaphragmatic extralobar sequestration, possibly because proximity to the diaphragm is associated with an increased prevalence of rhabdomyomatous dysplasia, a mesenchymal abnormality proposed as a potential early stage of pulmonary rhabdomyosarcoma. The overall malignancy risk across congenital lung malformations approaches 12 percent in published systematic reviews, with the extralobar sequestration subtype contributing an estimated 7 percent risk. These figures carry publication bias and must be interpreted with appropriate caution, but they provide a meaningful rationale for definitive histological diagnosis rather than indefinite observation. Beyond oncologic risk, IDEPS infection — though less frequent than in intralobar sequestration — can cause diaphragmatic elevation, impaired ipsilateral ventilation, dense adhesions, and edematous planes that dramatically complicate subsequent surgical dissection. Several reports cite infection rates of 16 to 31 percent in broader extralobar sequestration populations. Finally, the lesion's deep muscular confinement limits the reliability of long-term imaging surveillance; ultrasound access is limited, and repeated CT exposes a growing child to cumulative radiation without offering the histological certainty that resection provides. For all these reasons, surgical excision before twelve months of age is widely recommended. Delayed surgery — beyond one year — has been associated in some series with higher rates of respiratory symptoms at the time of intervention, likely because the growing lesion exerts progressive mass effect on surrounding structures. The defining surgical challenge of IDEPS is the uncertainty of intraoperative localization. No other congenital lung lesion so reliably resists preoperative prediction of the optimal approach. Minimally invasive surgery has become the predominant strategy, with thoracoscopy and laparoscopy each employed in roughly comparable proportions. Thoracoscopy reflects the left-sided predominance of the lesion and the familiarity of pediatric thoracic surgeons with minimally invasive thoracic approaches. Laparoscopy offers a panoramic view of the diaphragm from below, which can be useful when the lesion protrudes into the abdominal cavity or when the feeding artery arises from the abdominal aorta. Neither approach is universally superior. What the evidence clearly establishes is that a meaningful proportion of cases — approaching 15 percent in combined published series — ultimately requires a combined thoraco-abdominal approach because the lesion cannot be safely identified or resected from a single cavity. In some instances, a thoracoscopic exploration is followed by laparoscopic excision after the vessels are controlled; in others, the opposite sequence is necessary. One striking case in the literature required three separate operative approaches — thoracoscopy, followed by thoracotomy, followed by laparotomy — within a single anesthetic before the lesion was found and removed. That experience captures in concentrated form the intraoperative unpredictability that defines this condition. Surgeons must prepare both thoracic and abdominal setups before every case and must counsel families preoperatively about the realistic possibility of cavity extension, conversion to open surgery, or prolonged operative time. Median operative times in published series exceed two hours. When the lesion is identified, the operative steps consist of careful dissection from the surrounding diaphragmatic muscle, identification and secure ligation of the feeding artery, and complete excision of the mass. The feeding vessel must be controlled before proceeding, since inadvertent avulsion is the principal intraoperative hemorrhagic risk. Diaphragmatic repair may be required depending on the extent of tissue disruption. Postoperative complication rates are low — approximately 4 to 8 percent in combined series — and complications tend to be minor: self-limiting pneumothorax, small pleural effusions, or transient respiratory morbidity. No operative deaths have been reported in contemporary series. Hospital stay typically ranges from three to seven days. These are reassuring outcomes, but they reflect the experience of high-volume centers with specific expertise; the surgeon approaching a first or second IDEPS case must not interpret the published figures as a guarantee of straightforward execution. Intraoperative ultrasound guidance has been described as a useful adjunct for improving lesion localization during minimally invasive procedures, particularly when the lesion is small or when preoperative imaging has failed to precisely define its boundaries. Advanced three-dimensional CT reconstruction may help surgeons mentally rehearse anatomical relationships before entering the operating room. These tools are not yet standardized but represent a rational evolution in the preoperative and intraoperative toolkit for a condition that consistently challenges surgical localization. The broader category of atypical extralobar sequestrations — including intrapericardial variants, retroperitoneal variants, and cases with bilateral or multiple lesions — reinforces the principle that this family of malformations does not conform to predictable anatomical rules, and that diagnostic and operative flexibility must be the surgeon's default posture. What IDEPS ultimately demands of the surgeon is a combination of meticulous preoperative planning, genuine tactical flexibility in the operating room, and an understanding of the histopathological stakes that justify the effort. It is a condition that cannot be safely observed away. The lesion will not reliably involute, cannot be reliably surveilled, and carries both infectious and oncologic risks that accumulate silently over time. Complete surgical resection with histological examination remains the only strategy that addresses all of these concerns simultaneously. As the collective published experience continues to grow — slowly, given the extreme rarity of the condition — prospective multicenter registries will be essential to generate the evidence needed to standardize management. Until then, the surgeon who understands the anatomy, respects the intraoperative uncertainty, and prepares for every contingency will consistently achieve the outcomes this condition's rarity might otherwise obscure. References: 1- Huang D, Habuding A, Yuan M, Yang G, Cheng K, Luo D, Xu C: The clinical management of extralobar pulmonary sequestration in children. Pediatr Pulmonol. 56(7):2322-2327, 2021 2- Chakraborty RK, Modi P, Sharma S: Pulmonary Sequestration. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jul 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 3- Wang T, Zhao Z, Kong L, Lyu X, Cao X, Zhang X, Chen Q: Extralobar pulmonary sequestration: A case report and literature review. Clin Case Rep. 11(12):e8282, 2023 4- Rai A, S S, Rhakho V, Choudhary A, Kumar S: Extralobar Pulmonary Sequestration: A Rare Entity. Cureus. 16(7):e64977, 2024 5- Bertozzi M, Fusi G, Oreglio C, Fati F, Angotti R, Bindi E, Rizzo R, Guaná R, Midrio P, Ichino M, Morandi A, Noviello C, Papparella A, Gennari F, Nanni L, Cobellis G, Molinaro F, Volpe A, Morini F, Gazzaneo M, Riccipetitoni G: Intra-diaphragmatic extralobar pulmonary sequestration: Surgical approaches and outcome. J Pediatr Surg. 61(3):162863, 2026 6- Roveri M, Pedroni G, Preziosi A, Arcieri L, Marianeschi S, Macchini F, Zanini A: Intrapericardial Extralobar Pulmonary Sequestration: A Case Report and Systematic Review of a Unique Embryologic Variant. J Clin Med. 15(3):932, 2026 |
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