Synchronous papillary-medullary thyroid microcarcinoma: a case report.

Background: Papillary thyroid carcinoma is the most common type of thyroid carcinoma, making up 85-90% of all thyroid carcinomas. Medullary thyroid carcinoma is the third most common type of thyroid carcinoma, making up less than 5% of all thyroid carcinomas. However, synchronous papillary-medullary thyroid carcinoma is exceedingly rare and has not been well described historically. There have been fewer than 40 cases reported in the current literature. Case Description: In this case report we present a 65-year-old man with synchronous papillary-medullary thyroid carcinoma. A 65-year-old man presented with a symptomatic multinodular thyroid goiter. Ultrasound (US) confirmed bilateral thyroid nodules, and he was initially managed nonoperatively. Fine needle aspiration (FNA) biopsy of the left dominant nodule revealed atypia of undetermined significance (AUS) (Bethesda class III). Further assessment of the FNA specimen with ThyGeNEXT® (mutation panel) revealed no mutations and the ThyraMIR® (microRNA risk classifier) was negative, which classified the results as very highly likely to be benign. Due to worsening local compressive symptoms, a total thyroidectomy was performed. Final surgical pathology revealed incidental multicentric, multifocal micropapillary carcinoma foci from (0.1 to 0.5 cm), and a 0.3 cm medullary carcinoma in the left thyroid lobe on the background of nodular hyperplasia. Conclusions: Synchronous papillary-medullary thyroid carcinoma is a rare finding that should be considered in patients with symptomatic multinodular thyroid goiters. It is important to report this case to increase awareness and improve our understanding and management of these unusual carcinomas in the future.

Sudden death in Lesch-Nyhan disease.

To increase awareness of sudden and unexpected death in Lesch-Nyhan disease (LND) and to explore its potential causes, we report the anteceding clinical features and laboratory evaluations of five males with LND who ultimately experienced sudden and unexpected death, along with three additional males who suffered serious respiratory events during life. The ages of patients ranged from 2 to 45 years. The cause of sudden death in LND appears to have a respiratory rather than a cardiogenic basis. All cases cannot be linked readily with a single respiratory process. Instead, different respiratory processes appear to operate in different cases. These may include aspiration, laryngospasm, central apnea, cyanotic breath-holding spells, and high cervical spine damage. Better recognition of these processes will help to guide appropriate workup and management that could include chest imaging, endoscopy of the airways, polysomnography, electroencephalogram, and brain and/or spine imaging.

The biochemical basis of the neurobehavioral abnormalities in the Lesch-Nyhan syndrome: a hypothesis.

Lesch-Nyhan syndrome (LNS) is a rare X-recessive disorder that leads to virtually complete deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). Partial HPRT deficiency results in uric acid overproduction with subsequent hyperuricemia, nephrolithiasis, renal failure and gouty arthritis. In contrast, at complete HPRT deficiency, besides overproduction of uric acid neurological problems appear including spasticity, choreoathetosis, mental retardation, and compulsive self-mutilation. The cause for the uric acid overproduction has been clarified, but the connection between the enzyme deficiency and the neurological manifestations in LNS remains unclear. A hypothesis, which explains this relation, is proposed in the paper. The hypothesis has several important points most substantial of which is the accelerated biosynthesis of semiessential amino acid histidine that against the background of accelerated purine de novo biosynthesis results in 5-aminoimidazole-4-carboxamideribotide (AICAR) and histamine accumulation. The histamine and AICAR were determined to be the compounds that cause the neurobehavioral symptoms of LNS for several reasons. First, in the basal ganglia a balance between the direct (activating) and the indirect (inhibiting) pathways arising on the basis of the antagonistic and reciprocal dopamine-adenosine interactions normally exists. This balance can tonically regulate smooth voluntary movements and the activity of the thalamus, which, in turn, processes the afferent sensorimotor signals from the whole body to the all areas of the cerebral cortex and is concerned to modulate mental development and bring sensory information into awareness. Second, histamine is known to induce a selective damage in dopaminergic neurons inhibiting the direct dopaminergic pathway, which could lead to muscular rigidity, and slowness in initiating movements as well as tremor that are characteristic of Parkinsonism in LNS. Third, AICAribosid (AICAR breakdown product) is a potent adenosine A2a receptor antagonist inhibiting the indirect dopamine-adenosinergic pathway and, therefore, could be responsible for the choreoathetosis, dystonia and ballismus found in LNS. The excitatory-inhibitory disbalance in the basal ganglia could result in inadequate modification of the thalamus activity with subsequent mental retardation and symptoms that include the patients not being aware for their own bodies that could give rise to self-mutilation. Finally, a possibility for the creation of a new animal model that could exactly match the human LNS is proposed in the paper.