We here describe a patient with sarcoidosis and a coexisting schwannoma that presented as a steroid-resistant mass in the gallbladder wall. Intra-abdominal schwannomas have reportedly occurred in the intrahepatic duodenal ligament [2], pancreas [3], small mesentery [4], and colon [5]. To the best of our knowledge, only ten schwannomas in the gallbladder, including the present case, have been reported [6,7,8,9]. Schwannomas are histopathologically composed of spindle cells in a nuclear palisade arrangement and Verocay body formation [10]. On immunostaining, the spindle cells are characteristically strongly positive for S-100 protein and negative for desmin, smooth muscle myosin, SMA, c-KIT, CD34, and CD117 [11]. As for clinical features, schwannomas that develop in the abdominal cavity are often asymptomatic for a long time, eventually presenting with symptoms of compression of surrounding organs [2].
Schwannomas arising in the digestive tract can be easily accessible to endoscopic biopsy, whereas it is difficult to obtain a biopsy of the gallbladder to make a definitive diagnosis [2]. Schwannomas have no distinctive imaging findings and the preoperative diagnosis is often difficult. Multiple imaging modalities such as contrast-enhanced US, CT, and MRI may be useful in making a diagnosis. Color Doppler ultrasound reportedly shows well-defined hypodense lesions with no echoic enhancement [12]. CECT shows well-defined hypodense lesions with encapsulation and/or cystic degeneration [11], and MRI shows hypointensity on T1-weighted images and lack of homogeneity and hyperintensity on T2-weighted images [13, 14]. Contrast-enhanced US and CECT can evaluate the intra-tumor blood flow, enabling differentiation from malignant tumors [6].
In contrast, sarcoidosis is an inflammatory disease that is characterized by formation of granulomas (small nodules of immune cells) in the lungs, lymph nodes, and other organs. Sarcoidosis may be acute and resolve spontaneously, or be chronic and progressive [15]. More than 80% of cases occur in adults between 20 and 50 years of age [16]. Treatment is not indicated for patients with asymptomatic sarcoidosis because spontaneous resolution is common [16]. Treatment with corticosteroids should be considered for patients with significant symptomatic or progressive pulmonary disease or serious extrapulmonary disease [17]. An international consensus statement recommended prednisone (or its equivalent) at a starting dosage of 20 to 40 mg per day for 4 to 6 weeks [16]. If the patient’s condition is stable or improved, the dosage should be tapered slowly to approximately 5 to 10 mg per day.
To the best of our knowledge, no relationship between sarcoidosis and schwannoma has been documented. The differential diagnosis for both sarcoidosis and schwannoma is broad because of the nonspecific symptoms and diverse clinical presentations. Because many other diseases present with similar clinical, radiologic, and pathologic findings, infections and malignancy (e.g., lymphoma) should be ruled out if suspected [17].
Our patient’s schwannoma was complicated by her coexisting systemic sarcoidosis, which is an extremely rare combination. Because all lesions except for the one in the gallbladder were responsive to steroids, it was resected to obtain an accurate diagnosis, the rationale being that if it was not a sarcoid lesion, we could reduce her dosage of steroids.
In addition, in this case, the excised specimen showed a mixture of spindle-shaped lesions indicating a schwannoma and non-necrotic granulomatous lesions indicating sarcoidosis, which may have a component of neurosarcoidosis as reported by Bangiyev et al. [18].
