Clinical Characteristics and Imaging for the Differential Diagnosis of Pediatric Sellar Lesions

Clinical manifestation, tumor marker concentrations, and imaging can aid in the differential diagnosis of pediatric sellar and suprasellar lesions, according to study results published in Frontiers in Endocrinology.

Sellar and suprasellar lesions commonly present initially as central diabetes insipidus but can be caused by a variety of etiologies. In a retrospective analysis of pediatric patients (≤14 years of age) in the Peking Union Medical College Hospital database in China, researchers aimed to characterize pediatric sellar and suprasellar lesions that initially manifested as central diabetes insipidus, with the goal of improving differential diagnosis and early treatment initiation.

The study included 55 pediatric patients (mean age, 10.3 years; 69.1% girls) with initial symptoms of polyuria and polydipsia who had confirmed sellar or suprasellar lesions. The mean interval from onset of symptoms to diagnosis was 22.9 months. Serum levels of several endocrinological factors were measured and sellar and suprasellar lesions were assessed by magnetic resonance imaging (MRI) scans. Histopathological diagnosis of lesions was performed in 43 patients (78.2%) who underwent transsphenoidal surgery, 6 (10.9%) who underwent craniotomy, and 6 (10.9%) who underwent bone marrow biopsy.

Germ cell tumors were responsible for the majority (74.5%) of observed lesions. Langerhans cell histiocytosis (LCH; 18.2%) and craniopharyngiomas (7.3%) accounted for the remainder of lesions observed. Germ cell tumors and craniopharyngiomas presented more often in girls. A majority of patients (90.9%) presented with anterior pituitary dysfunction, characterized predominantly by growth factor deficiency. MRI showed that the pituitary bright spot disappeared in all patients and 94.5% of patients presented with a thickened pituitary stalk. Almost all lesions (96.4%) presented within the suprasellar region.

Children with germ cell tumors were most likely to have additional symptoms, including short stature (48.7%), headache (48.7%), inappetence (46.3%), and visual defects (24.4%). Six children also experienced deficiencies in pubertal development. Serum β-human chorionic gonadotropin (HCG) levels were elevated (>5 U/L) in 22.0% of children and 64.1% had elevated β-HCG levels in the cerebrospinal fluid (CSF). All germ cell tumors presented with T1 hypointensity or isointensity and 95.1% presented with T2 isointensity or hyperintensity on MRI. Heterogeneous and homogeneous enhancement occurred at an approximately equal ratio. Pineal body lesions also occurred in 20% of patients.

Additional clinical manifestations were less common in patients with LCH and craniopharyngiomas, though short stature and visual defects presented in both groups. Patients with LCH also experienced headache (50%), nausea (30%), and amenorrhea (10%). Extrasellar lesions occurred in 9 patients, including bone (77.8%), thyroid (55.6%), lung (44.4%), and skin (11.1%) lesions. Only 1 patient with craniopharyngioma underwent examination of tumor marker levels, which were all within the normal range. Three patients with LCH had slightly elevated CSF β-HCG levels (6-7 IU/L), but all other tumor marker levels were within normal range. Most cases of LCH presented with T1 and T2 isointensity on MRI, and all patients exhibited homogeneous enhancement. In contrast, patients with craniopharyngioma predominantly presented with T1 and T2 hyperintensity and heterogeneous enhancement.

The study authors suggested that presurgical diagnoses of sellar and suprasellar lesions should consider not only the clinical presentation of symptoms but also the presence of serum and CSF tumor markers as well as MRI characteristics. These results may be aided by biopsy and histopathology, which can differentiate the lesion types based on their physical characteristics and immunohistochemical staining. Germ cell tumors exhibited a gray-white appearance with a fish-meat pattern and stained positive for CD117, placental alkaline phosphatase (PLAP), or octamer binding transcription factor (OCT) 3/4 in all cases. Craniopharyngiomas tended to be oil-like and were mainly characterized by cholesterol crystals and inflammatory cells. Only 30% of patients with LCH underwent lesion biopsy, but these presented with a gray-white and rubbery appearance and were positive for CD1a and S100 in all cases.

The researchers noted that the retrospective nature of the study limited data collection and prevented the coordination of a standardized assessment of each patient.

They also acknowledged that many of the early symptoms of sellar and suprasellar lesions, including polyuria and polydipsia, are easy to ignore, but more emphasis should be placed on early detection. “Approximately three-quarters of our patients had symptoms or signs for more than 6 months before their diagnoses, and the diagnostic delay could be up to 10 years,” they wrote.

The results of this study provide useful data to improve the differential diagnosis of SSR lesions. “For pediatric [sellar and suprasellar] masses that initially present as [central diabetes insipidus], the assessment of clinical manifestations and the measurement of anterior pituitary function and tumor markers in serum or CSF are important for the diagnosis and differential diagnosis of these lesion. MRI is also an effective tool for the diagnosis of [sellar and suprasellar] lesions.”

Reference

Ji X, Wang Z, Wang W, et al. Clinical characteristics of pediatric patients with sellar and suprasellar lesions who initially present with central diabetes insipidus: a retrospective study of 55 cases from a large pituitary center in China. Front Endocrinol (Lausanne). 2020;11:76.