Key clinical message:  Adrenal schwannomas, though typically benign and often incidentally kndiscovered, can present significant postoperative challenges such as chylothorax and chylous ascites. Early recognition of these complications, characterized by milky discharge from surgical sites, abdominal distention, and pleural effusion, is essential. Effective management requires a multidisciplinary approach, including dietary modifications, pharmacotherapy with somatostatin analogs, and interventions like thoracentesis and paracentesis. This comprehensive care strategy is vital for mitigating symptoms, promoting recovery, and improving patient outcomes.Abstract: Schwannomas originating from the Schwann sheath of peripheral or cranial nerves are rare tumors, commonly found in the head and neck region or extremities. Adrenal schwannomas, however, are exceedingly rare, accounting for less than 1% of all adrenal tumors. Here, we present a case of a 31-year-old Caucasian woman diagnosed with an adrenal schwannoma, which was incidentally discovered during imaging studies for an unrelated issue. Following open adrenalectomy, the patient developed chylous ascites and coexistent chylothorax, posing a diagnostic challenge and necessitating a multidisciplinary approach to management. This case highlights the complexities involved in diagnosing and managing rare adrenal masses and underscores the importance of a thorough clinical evaluation and vigilant postoperative monitoring.Keywords: Adrenal schwannoma, Chylous ascites, Chylothorax, Case report, Multidisciplinary management.Introduction:Schwannomas are rare tumors, originating from the Schwann sheath of the peripheral or cranial nerves. Schwannomas are common in the head and neck region or the extremities; visceral involvement of schwannomas is extremely rare. Only a handful of cases of adrenal schwannomas are reported [1] and overall, adrenal schwannomas make up less than 1% of all adrenal tumors, 1-3% of total schwannomas, and 0.4% of the retroperitoneal tumor [2]. In recent years, the advancements in imaging techniques have resulted in the inadvertent identification of more adrenal tumors, however, it is exceptionally difficult to make a preoperative diagnosis of adrenal schwannoma, and determining whether a tumor is an adrenal schwannoma can only be definitively established by pathologic examination with immunohistochemical staining [3, 4]. Adrenalectomy is the primary method used to manage adrenal tumors, although it can be linked with several complications, despite its generally acknowledged safety. Two rare yet severe complications that may arise following retroperitoneal surgery are chylothorax and chylous ascites [5]. We are presenting a rare patient who was diagnosed with adrenal schwannoma, and post-operatively, the case was complicated with chylous ascites and coexistent chylothorax.Case History/ Examination:A 31-year-old Caucasian woman with an unremarkable medical history, presented to the urology clinic due to a left adrenal mass initially discovered several years ago. Despite a previously unremarkable metabolic workup, recent imaging studies revealed an enlargement of the mass with atypical characteristics, prompting further investigation. Routine blood and hormonal workups, including serum cortisol, dehydroepiandrosterone sulfate (DHEAS), metanephrine, and normetanephrine, along with 24-hour urinary metanephrine and normetanephrine, again were within normal limits. However, due to the progressive increase in size, adrenalectomy was deemed necessary and performed.Subsequent histopathological examination following open adrenalectomy identified the mass as a cellular schwannoma, a rare finding in this location.Although the surgical procedure proceeded smoothly, the patient experienced a transient complication characterized by a milky discharge from one of the surgical incisions, which resolved spontaneously without intervention. However, a month following the surgery, she presented with symptoms of shortness of breath, abdominal distention, and a significant weight gain, prompting readmission to the hospital.Methods (Differential Diagnosis, Investigations and treatment):On readmission, Imaging studies revealed the presence of ascites, omental nodularity, retroperitoneal lymphadenopathy, and a large right-sided pleural effusion, indicative of a potential complication or metastatic spread (Figure 1,2,3). To address these concerns, therapeutic interventions including thoracentesis, and paracentesis were performed, which led to the diagnosis of chylothorax and chythous ascites (Figure 4). The patient was commenced on a high protein, low-fat diet regimen and initiated on somatostatin analog octreotide therapy to manage her symptoms and potentially mitigate further disease progression, and placement of an abdominal drain was performed, facilitating the removal of accumulated fluid. Following these interventions, there was a notable improvement in the patient’s clinical condition, prompting discharge from the hospital.Conclusion and Results (outcome and follow up)After close outpatient follow-up to monitor response to treatment and assess for any recurrence or new developments. This comprehensive approach underscores the complexity of managing rare adrenal masses and highlights the importance of a multidisciplinary approach in ensuring optimal patient outcomes. The case highlights the diagnostic intricacies regarding adrenal schwannoma, emphasizing that it is essentially a diagnosis of exclusion. Despite these challenges, it is imperative to consider adrenal schwannoma in the differential diagnosis of incidentally discovered adrenal masses, as demonstrated in this case. Moreover, the case underscores the importance of maintaining a heightened suspicion for chylous effusion in patients presenting with incision site drainage, as this complication can lead to prolonged hospitalizations and necessitate multiple procedures, as observed in our experience. Thus, clinicians should remain vigilant in recognizing and managing such complications to ensure optimal patient outcomes.Discussion:Schwannomas are tumors that arise from Schwann cells, which are cells that form the myelin sheath surrounding nerve fibers in the peripheral nervous system [6]. Theodore Schwann, a prominent German histologist, and physiologist, first characterized Schwann cells (1810–1882). Later on, Schwannomas was first described by Verocay in 1908 (7, 8), and then in 1920, Nils Ragnar Eugène Antoni identified two contrasting patterns within schwannomas [6].Schwannomas are usually benign [9]. However, it is important to note that between 5-18% of Schwannomas are linked to von Recklinghausen’s disease. When this condition is present, Schwannomas tend to be malignant and have a higher likelihood of appearing in multiple locations.Adrenal Schwannomas are believed to arise from one of the two sets of nerves that innervate the adrenal gland’s medulla; vagus or phrenic nerves. The schwannomas emerge from the medulla and compress the adrenal cortex as they grow [10].Adrenal Schwannomas are more commonly observed in females during the second or fifth decade of life, indicating a tendency towards occurrence in middle-aged women (11). Typically, these tumors do not exhibit any symptoms and are found unexpectedly during imaging studies conducted for unrelated purposes. Retroperitoneal schwannomas are often incidentally discovered during evaluations for nonspecific abdominal pain, typically exceeding 4cm in size at diagnosis. Imaging of a retroperitoneal mass localized to the adrenal region commonly presents a range of potential differentials, including adrenal adenoma, pheochromocytoma, myelolipoma, adrenocortical carcinoma, ganglioneuroma, and adrenal metastasis. Surgical excision remains the gold standard treatment for retroperitoneal schwannomas, providing both diagnostic confirmation and symptom relief [12, 13, 14]. As discussed above, chylous ascites and chylothorax are rare but serious complications that can occur after retroperitoneal surgery [5]. Postoperative chylous ascites (CA) arise due to inadvertent intraoperative injury to the lymphatic system, resulting in the leakage of lymph into the peritoneal cavity. The diaphragm then plays a crucial role in facilitating the absorption of chylous ascites into the thorax and leading to chylothorax [15, 16]. As far as treatment is concerned, in cases like ours, it is advisable to pursue a conservative approach involving a diet high in protein and low in fat, particularly rich in Medium-Chain Triglycerides (MCTs). MCTs are absorbed directly by intestinal cells and transported as free fatty acids (FFA) and glycerol to the liver via the portal vein, bypassing the thoracic duct [17]. Continuous intravenous high-dose somatostatin or its subcutaneous analog octreotide effectively reduces chyle formation in postoperative lymphatic leaks [5]. Alternatively, orlistat, an inhibitor of lipase activity, also shows promise in managing chylous ascites [18]. Other treatment options include peritoneal and pleural taps, chest tube drainage, and abdominal drain placement as performed in our case [17]. Surgical repair is typically considered after a 4-week trial of conservative management, with peritoneovenous shunting reserved for refractory cases [19]. When chyle reaccumulates rapidly in the pleural space despite conservative measures and abdominal surgical repair is not feasible, obliteration of the pleural space should be considered [20].AUTHOR CONTRIBUTIONSAnam Umar: Conceptualization; Data curation; Supervision; writing – review and editing. Amber Faquih: Data curation; writing – review and editing. Muhammad Bilal: Data curation, writing – review and editing. Jeffery Garner conceptualization; writing – review and editing.References:1.    Târcoveanu E, Dimofte G, Bradea C, Moldovanu R, Vasilescu A, Anton R, Ferariu D. Adrenal schwannoma. JSLS. 2009 Jan-Mar;13(1):116-9. 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