A rare case of cutaneous granular cell tumor with unusual Melan-A expression in a child.

Granular cell tumors (GCTs) are rare, indolent neoplasms classically characterized by eosinophilic granular cytoplasm, infiltrations of polygonal cells in the collagenous stroma, and pustulo-ovoid bodies of Milian. We describe a case of a 10-year-old female presenting with a GCT of the upper arm, remarkable for positive Melan-A expression without additional melanocytic features. The differentiation between granular cells versus melanocytic neoplasms carries significant implications for clinical management, and such diagnoses should be considered carefully in the setting of unusual immunophenotypes.

Metastatic pulmonary calcification on bone scintigraphy of a patient with lupus nephritis and end-stage renal disease.

A 65-year-old male complaining of low back pain was noted to have diffuse, homogenous bilateral lung uptake on Tc-99m methylene diphosphate (Tc99m-MDP) bone scintigraphy. The patient had no prior history of pulmonary disease with no apparent respiratory symptoms at time of imaging, but did endorse a long history of lupus nephritis and end-stage renal disease on hemodialysis. Review of prior chest CT and chest X-ray imaging over the last 5 years revealed diffuse ground-glass opacities and extensive parenchymal calcifications, consistent with metastatic pulmonary calcification. These radiological findings were further corroborated by laboratory studies, which demonstrated longstanding secondary hyperparathyroidism with a most recent work-up including an iPTH level of 1251 pg/mL. The differential diagnosis of bilateral, diffuse Tc99m-MDP uptake on bone scintigraphy includes tracer contamination, pulmonary etiologies such as pleural effusion or mesothelioma, metabolic diseases such as metastatic pulmonary calcification, and genetic diseases including pulmonary alveolar microlithiasis. In the setting of longstanding renal dysfunction and chronic hypercalcemia as in this patient, such radiological findings are a classic presentation of metastatic pulmonary calcification.

Second window ICG predicts postoperative MRI gadolinium enhancement in high grade gliomas and brain metastases.

A prospective trial evaluating the utility of second window indocyanine green (SWIG) in predicting postoperative MRI gadolinium enhancement was performed on high-grade gliomas (HGGs) and brain metastases. Compared to white light alone, SWIG demonstrated a higher sensitivity, negative predictive value, and accuracy in predicting residual neoplasm on MRI. The specificity of SWIG for predicting MRI enhancement was higher in HGGs than brain metastases. Clinically, near-infrared (NIR) imaging was better able to predict tumor recurrence than postoperative MRI. These results illustrate how SWIG is able to take advantage of gadolinium-like distribution properties to extravasate into the tumor microenvironment, enabling guidance in surgical resection. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21204.