Artifacts are noncerebral waveforms that may mimic or obscure cerebral activity. External (nonphysiologic artifacts) are produced outside the body whereas internal (physiologic artifacts) are produced by body organs other than the brain. Electrode artifact may have a spiky, periodic, or rhythmic appearance. Characteristically, it is limited to the involved electrode with no field. Sweat artifact may involve multiple. Eye movement and glossopharyngeal artifact may mimic frontal rhythms. EKG artifact (corresponding with QRS complexes) may be confused with periodic discharges. Ventilatory artifact may be confused with bursts of cerebral activity. Characteristically, it corresponds to the respiratory rate. Head tremor presents as occipital predominant rhythmic artifact. Maneuvers and devices such as bed-percussion, continuous renal replacement therapy, and extracorporeal membrane oxygenation, CPR, and even brushing teeth may lead to ictal appearing rhythmic artifacts. Discharges associated with cortical myoclonus are best appreciated in the central channels as these are relatively free of muscle artifact. Chewing artifact may electrographically mimic a generalized tonic clonic seizure. Close observation of the patient and the surrounding equipment either in person or on video is the key to diagnosing the cause of an artifact and avoid misdiagnosing it as cerebral activity. [191 words/1168 characters]

Pathologists often encounter soft tissue neoplasms while examining biopsies and excisions from the skin. Soft tissue neoplasms are classified along their line of differentiation and include fibroblastic, myofibroblastic and fibrohistiocytic tumors, smooth muscle tumors, skeletal muscle tumors, neural tumors, lipomatous tumors, vascular tumors, pericytic and perivascular tumors and tumors of uncertain differentiation. These tumors can be categorized as benign, intermediate (locally recurrent/aggressive), intermediate (rarely metastasizing) and malignant (locally recurrent/aggressive with significant metastatic potential). Histologic diagnosis, grading and staging is imperative for prognostication and treatment. The continually expanding array of molecular diagnostics techniques has identified numerous novel gene alterations in soft tissue neoplasms that has enabled identification of new diagnostic entities with accompanying diagnostic and surrogate immunohistochemical markers. In this chapter we will review many soft tissue neoplasms and highlight important immunohistochemical markers.

Artifacts are EEG waveforms not generated by the brain. The main purpose of recognizing artifacts is to avoid mistaking them from seizures. They may originate from other body organs (internal) or environmental sources (external). Common internal artifacts include ocular (eye movement), glossokinetic (tongue movement), cardiac (ECG), myogenic (muscle activity), or sweat-sway artifact (skin). Common sources of external artifact include electrodes, ventilators, suction devices, bed percussion, chest compression, and various medical devices. Many commonly used medications are associated with EEG changes. These include excessive alpha and beta activity (e.g., barbiturates and benzodiazepines), theta and delta slowing (antiseizure and psychotropic medications), spike and sharp waves (clozapine), and rhythmic and/or periodic patterns (cefepime). EEG patterns of common intravenous and inhalational anesthetic agents are also described in this chapter.