What is important to know about extrapulmonary sarcoidosis?

A 14-year-old male patient presented with epistaxis and high blood pressure. His past medical history revealed Rolandic epilepsy since 2015. On admission, further investigations revealed normal cardiovascular examination, normal levels of creatinine and elevated plasmatic renin. A CT scan was performed to establish the cause of hypertension.

Unenhanced and enhanced abdominal multislice CT evaluation (Figure 1) with coronal reconstructions (Figure 2A and Figure 2B) revealed hepatomegaly, a left liver lobe hypoenchancing nodule, splenomegaly, multiple abdominal lymphadenopathies and ill-defined multiple hypoenchancing lesions, in both kidneys. The chest X-ray was normal (Figure 3). After 2 months an abdominal MRI was performed in T1 weighted image with FatSat, SSFSE with short TE (Figure 4) and long TE, diffusion (Figure 5) and with extracellular paramagnetic gadolinium-based contrast i.v. injection using a 3D T1 FS acquisition in axial (Figure 6) and coronal plane. All renal lesions have disappeared, and also retroperitoneal adenopathies are without any MRI pathological appearance.

Sarcoidosis is a multisystemic inflammatory disease characterized by the existence of non-caseating granulomas which consist in masses with macrophages, mononuclear and epithelioid cells, along with T cells. The aetiology of this disorder is unknown, but an abnormal immune response could be the cause[1,2]. This disease is ubiquitous, with a higher prevalence in young and middle-aged patients, respectively with a slight female predominance [3]. The lungs manifestations are the most frequent in sarcoidosis, along with skin, liver, spleen, lymph nodes, nervous system, heart and renal involvement [4].

Prevalence of sarcoidosis is less common in children and they often present with acute symptomatology and multisystemic involvement, such as hepatosplenomegaly, lymphadenopathy, lung disease and uveitis [5]. Pediatric sarcoidosis has two forms, one that has an early onset, before 5 years old, and one with late-onset which is characterized by multi-system disease [6].

Renal manifestations are rare in sarcoidosis, with no certain data about prevalence in general population. The most common finding in biopsies in these cases is the granulomatous tubulointerstitial nephritis [7]. Noncaseating cell granulomas can be found isolated or associated with extrarenal disorder [6].

Patients suspected of having sarcoidosis should have a chest radiography, which is the first imaging step used for pulmonary sarcoidosis, but for extrapulmonary disease, it is often required ultrasound, CT and magnetic resonance (MR) imaging [8]. Thin-section CT of the thoracic cavity highlights multiple well-defined perilymphatic micronodules in the pulmonary parenchyma and mediastinal adenopathy [8].

The most common ultrasound findings in abdominal sarcoidosis are hepato-splenomegaly, hypoechoic masses and enlarged lymph nodes [9].

Regarding the renal lesions, they appear hypodense and hypovascular on CT scans, with multiple patterns of enhancement, from spotted or striated to mass-like lesions, less frequent. The kidneys can be atrophied or with increased dimension [10]. On MRI, ill-defined masses can be found, with homogenous or heterogenous structure, frequently isointense to the surrounding renal parenchyma on unenhanced T1 and T2-weighted sequences. After gadolinium-based intravenous contrast administration, the lesions demonstrate delayed and poor enhancement to the normal renal cortex [11].

The diagnosis of extrapulmonary sarcoidosis, in cases with normal chest X-ray or normal CT lungs, is possible correlating clinical and imagistic findings with the histopathologic results of non-caseating granulomas on biopsy, pathology remaining the gold standard examination, after the exclusion of other causes of granuloma formation, such as infectious diseases or neoplasms, and of course, taking into account the favourable evolution under the corticosteroid treatment.

Outcome

Taking into account the CT aspects a renal and lymph-node biopsy were performed. The pathological analysis from the biopsied kidney lesion discovered granulomatous tubulointerstitial nephritis, while the biopsied lymph node pathological examination showed multiple non-caseating cell granulomas, suggesting the diagnosis of sarcoidosis. After the coticotherapy begun, the clinical symptoms and imaging findings improved.