Polycythemia vera (PV) is a clonal myeloproliferative neoplasm primarily caused by the JAK2V617F mutation, present in 95% of patients. It results in erythropoietin-independent hematopoietic proliferation, erythrocytosis, increased hematocrit (Hct), leukocytosis, thrombocytosis, and hyperviscosity, predisposing patients to thrombotic events and neurologic deficits, including erythromelalgia and pruritus. Neurologic manifestations can occur, such as transient ischemic attack (TIA) and stroke. We report an 83-year-old woman, PV patient who presented with chorea and magnetic resonance imaging (MRI) of her brain showed pachymeningeal enhancement (dural-arachnoid enhancement); this radiological finding is most commonly described in intracranial hypotension, autoimmune conditions, infection, and neoplastic processes and has not been reported in PV. Laboratory findings included complete blood count (CBC) showed severe erythrocytosis, moderate leukocytosis with moderate, mild thrombocytosis; bone marrow (BM) aspiration and biopsy showed hypercellular BM and marked megakaryocytic hyperplasia; and positive JAK2V617F mutation with 80% JAK2 DNA, suggestive of PV as the underlying cause. The patient underwent phlebotomy and was started on Aspirin. Following treatment, she showed dramatic improvement in choreiform movements. Hydroxyurea 500 mg three times daily was subsequently added, leading to complete hematologic response and resolution of pachymeningeal thickening on follow up MRI. This case suggested association between polycythemia vera and choreiform movements and a possible mechanism is proposed.

Polycythemia is defined as an elevation of age and sex - adjusted hematocrit. While Polycythemia vera (PV) is a myeloproliferative neoplasm caused by JAK2 mutations leading to an autonomous proliferation of red blood cells. Most cases of polycythemia seen in general practice represent relative polycythemia or are secondary to other causes. Secondary erythrocytosis is most often due to chronic hypoxia, the use of erythropoietin-stimulating drugs such as androgens or SGLT2 inhibitors or erythropoietin -secreting tumors. Relative polycythemia results from chronic plasma volume contraction. Rarely, hereditary erythrocytosis may be a cause of polycythemia. In this review we outline our diagnostic approach to patients with polycythemia, focusing on identifying secondary causes. We suggest that when polycythemia is isolated, secondary and hereditary causes should be considered initially. If polycythemia is accompanied by leukocytosis or thrombocytosis, the initial investigations should be testing for JAK2 mutations and serum erythropoietin levels. Polycythemia vera is characterized by headache, visual disturbances, pruritus, erythromelalgia and splenomegaly. Treatment includes phlebotomy, low-dose aspirin, and cytoreductive agents. In secondary polycythemia, there are no clear guidelines regarding the desired hematocrit and management should be individualized to treat the cause. Phlebotomy is the only modality used to lower the hematocrit when this is required. A systematic clinical approach that prioritizes the exclusion of secondary causes before genetic testing may prevent unnecessary investigations and enable focused, effective patient care.

Red ear syndrome (RES) is a rare disorder characterized by episodic erythema, warmth, and burning pain of the external ear. RES is frequently associated with migraine. We report the case of a 35-year-old male with a long-standing history of poorly controlled migraine who presented with recurrent bilateral auricular erythema and burning pain, predominantly affecting the left ear. Symptoms were triggered by migraine attacks, heat exposure, and ear manipulation and relieved by cooling measures. Clinical examination, laboratory investigations, and imaging were normal. RES was diagnosed after excluding infectious and inflammatory causes. Treatment with indomethacin and magnesium resulted in complete symptom resolution. RES should be considered in patients with recurrent auricular erythema and burning pain, particularly in those with migraine. Careful clinical assessment and systematic exclusion of alternative diagnoses are crucial for identifying RES and preventing inappropriate management.

Gain-of-function mutations in SCN9A, encoding the voltage-dependent Nav1.7 sodium channel, cause three autosomal-dominant disorders associated with severe pain: primary erythromelalgia, paroxysmal extreme pain disorder (PEPD), and small fiber neuropathy. On the other hand, biallelic loss-of-function mutations have been linked to impaired pain perception. Notably, the coexistence of both hyperalgesia and hypoalgesia within the same patient harboring the I234T variant has been reported in three independent patients to date. We report a 7-year-old girl harboring co-occurring SCN9A (I234T) and PRRT2 variants who presented with paroxysmal extreme pain disorder, contradictory analgesia, sensitivity to heat, and intractable head-drop attacks. Based on the genetic and clinical analyses, she was diagnosed as having PEPD and PRRT2-related paroxysmal dyskinesia. The intractable head-drop attacks were considered as paroxysmal non-kinesigenic dyskinesia. In addition, she exhibited easy fatigability and hypotonia. Taken together with her cold, cyanotic feet, these findings suggest that she may have also had small fiber neuropathy.

Mutations in the SCN9A gene, which encodes the sodium voltage-gated channel alpha subunit 9 on chromosome 2 (Nav1.7), are extremely rare and play a crucial role in pain signaling. Depending on the type of mutation, the clinical presentation of these mutations can vary widely from hyperactive pain phenotypes such as primary erythromelalgia to hypoactive pain phenotypes manifesting as congenital insensitivity to pain. Despite multiple descriptions in the literature of pain-associated behaviors in sodium voltage-gated channelopathies, there are no perioperative guidelines in this patient population that can be used to manage pain-associated procedures. Incorporating reported insights from pain literature into an anesthetic plan may improve perioperative patient satisfaction and outcomes. We present a case of a patient with a novel SCN9A mutation (c.3019C>T) who underwent a common surgical procedure and suffered atypical complications. We propose that her SCN9A mutation may have contributed to these sequelae and recommend a greater familiarity with sodium channelopathies-especially those attributed to the SCN9A gene-to improve perioperative management.

Dissipation of body heat, essential to human life, is largely achieved through sweating. If sweating does not occur normally-as in patients with hypohidrosis (reduced sweating) or anhidrosis (lack of sweating)-the ability to dissipate heat via evaporative mechanisms is overwhelmed. Body temperature may rise, leading to heat-related illness, including heat intolerance, hyperthermia, heat exhaustion, heat stroke, and even death. In patients seen by a dermatologist, anhidrosis may underly and contribute to their symptoms and signs but may be difficult to detect given a limited availability of tools to measure anhidrosis. An association between anhidrosis and skin symptoms including flushing syndromes (eg, facial flushing and erythromelalgia) and widespread skin symptoms (eg, itching, burning, numbness, or tingling, and paresthesias) has recently been described. This review explores the existing dermatologic literature on anhidrosis including clues to the pathophysiology of these disorders, its relationship to skin diseases and symptoms, the tests currently available, and approaches to management. Recognition of an underlying anhidrosis by dermatologists may be important for providing optimal management for patients with heat-related symptoms.