Primary Thymic Mucinous Adenocarcinoma with Extensive Punctate and Amorphous Calcifications: A Case Report

BACKGROUND: Primary thymic mucinous adenocarcinoma is an extremely rare and aggressive tumor with poor prognosis. The tumor may present as a heterogeneous solid or cystic mass accompanied by calcifications. However, clinical and radiologic features of the tumor are not well known due to the rarity of the disease, which makes accurate diagnosis difficult. CASE PRESENTATION: Here we present a rare case of primary thymic mucinous adenocarcinoma in the anterior mediastinum, including computed tomography (CT) and magnetic resonance imaging (MRI) findings. Chest computed tomography revealed a large anterior mediastinal mass with extensive calcifications with poor enhancement. MRI showed that anterior mediastinal mass showed intermediate signal intensity on T1-weighted images (T1WI), high SI on T2-weighted images (T2WI), and heterogeneous enhancement. Biopsy was performed and the anterior mediastinal tumor was diagnosed as thymic mucinous adenocarcinoma by histopathologic examination and immunohistochemical staining. CONCLUSION: Thymic mucinous adenocarcinomas could be included in differential diagnoses of anterior mediastinal tumors showing extensive calcification, and common imaging findings of mucinous adenocarcinoma such as T2 high signal intensity and heterogeneous enhancement on MRI may be helpful to diagnose thymic mucinous adenocarcinoma.

Technical development of transcutaneous electrical nerve inhibition using medium-frequency alternating current.

BACKGROUND: Innovative technical approaches to controlling undesired sensory and motor activity, such as hyperalgesia or spasticity, may contribute to rehabilitation techniques for improving neural plasticity in patients with neurologic disorders. To date, transcutaneous electrical stimulation has used low frequency pulsed currents for sensory inhibition and muscle activation. Yet, few studies have attempted to achieve motor nerve inhibition using transcutaneous electrical stimulation. This study aimed to develop a technique for transcutaneous electrical nerve inhibition (TENI) using medium-frequency alternating current (MFAC) to suppress both sensory and motor nerve activity in humans. METHODS: Surface electrodes were affixed to the skin of eight young adults to stimulate the median nerve. Stimulation intensity was increased up to 50% and 100% of the pain threshold. To identify changes in sensory perception by transcutaneous MFAC (tMFAC) stimulation, we examined tactile and pressure pain thresholds in the index and middle fingers before and after stimulation at 10 kHz. To demonstrate the effect of tMFAC stimulation on motor inhibition, stimulation was applied while participants produced flexion forces with the index and middle fingers at target forces (50% and 90% of MVC, maximum voluntary contraction). RESULTS: tMFAC stimulation intensity significantly increased tactile and pressure pain thresholds, indicating decreased sensory perception. During the force production task, tMFAC stimulation with the maximum intensity immediately reduced finger forces by ~ 40%. Finger forces recovered immediately after stimulation cessation. The effect on motor inhibition was greater with the higher target force (90% MVC) than with the lower target (50% MVC). Also, higher tMFAC stimulation intensity provided a greater inhibition effect on both sensory and motor nerve activity. CONCLUSION: We found that tMFAC stimulation immediately inhibits sensory and motor activity. This pre-clinical study demonstrates a novel technique for TENI using MFAC stimulation and showed that it can effectively inhibit both sensory perception and motor activity. The proposed technique can be combined with existing rehabilitation devices (e.g., a robotic exoskeleton) to inhibit undesired sensorimotor activities and to accelerate recovery after neurologic injury.