A 29-year-old, non-vegetarian woman was admitted to our hospital because of hyperpigmentation over the dorsa of the fingers, toes (fig. ), and trunk (fig. ), along with intermittent numbness in the plantar region of the foot that began 2 months before admission. The numbness and hypoesthesia were initially limited to the plantar region of the foot; subsequently, these symptoms ascended to both lower legs 2 weeks before admission. The patient noted weakness in both legs, an unsteady gait, and a tendency to fall when walking. Numbness in the fingertips was also noted. The patient's medical history was not significant, and her family history was unremarkable.\nOn physical examination, her conjunctivae and mucous membranes were slightly pale, whereas her tongue appeared normal. Multiple, asymptomatic, hyperpigmented macular patches were noted on the trunk (fig. ), and no rash or dermatitis had preceded the onset of hyperpigmentation. Neurological examination revealed weakness based on hyporeflexia in all limbs and the results of manual muscle tests (MMT 4+/5). Impaired pinprick sensations below the second thoracic dermatome, poor joint positions, and vibration sensations over both lower limbs were recorded. A broad-based ataxic gait and a positive Romberg sign were also noted. There were no atypical cerebellar signs. In addition to the observed symptoms, the patient reported mild constipation, a bitter taste in the mouth, and hair loss.\nLaboratory investigations revealed normocytic anemia (hemoglobin, 10.7 g/dl [normal range, 12.0–16.0 g/dl]; mean corpuscular volume, 94.1 fl [normal range, 79–100 fl]), leukopenia (white blood count, 4.41 × 103/µl [normal range, 4.5 × 103−11 × 103/µl]), and thrombocytopenia (platelet count, 114 × 103/µl [normal range 150 × 103−400 × 103/µl]). A low vitamin B12 level (204 pg/ml [normal range 211–911 pg/ml]) and high serum homocysteine level (33.35 µmol/l [normal range 3.70–13.90 µmol/l]) were noted. Levels of human immunodeficiency virus antibody, the autoimmune profile, and levels of folic acid and endocrine hormones were within the normal ranges. A nerve conduction velocity test revealed polyneuropathy in the lower legs. Analysis of the cerebrospinal fluid revealed normal protein levels and cell counts. Examination of skin biopsy specimens showed basal layer hyperpigmentation with melanin incontinence and focal mild acanthosis.\nWe reevaluated the patient's medical history, taking into account the possibility of a vitamin B12 deficiency. The patient reported that she had started using N2O at parties in recent years. The frequency of N2O use was half a whipped cream propellant cartridge (approximately 7.0 liters of N2O may be released from each cartridge) daily for the last 2 years, and 1 month before admission, this had increased to 1 propellant cartridge daily. The patient received intramuscular injections of 1,000 µg vitamin B12 daily for 1 week and then weekly for 1 month. After 4 weeks of treatment, the pigmented lesions showed clinically significant improvement (fig. , fig. ).
Sudden-onset chest pain for 1 d.\nA 29-year-old man complained of sudden precordial pain with no remission for 1 d prior to hospital admission but denied hemoptysis, dyspnea, or syncope. He sought evaluation and was admitted for the purpose of intensive examination and treatment.\nThe patient had been addicted to N2O for 1 year; as a result, peripheral neuropathy had occurred and was treated with vitamin B12 (Vit B12). His medical history included poor blood glucose control and anxiety. However, he had no history of thrombosis, malignant tumor, recent trauma, or prolonged air travel.\nThe patient has smoked over 13 pack-years and did not have alcoholism or a positive family history.\nThe initial assessment revealed that the patient was overweight and fragile, with a body mass index of 31.12 kg/m2, temperature of 36.3 °C, blood pressure of 110-120/70-80 mmHg, heart rate over 110 beats/min, respiratory rate over 30 breaths/min, and pulse oximetry of 93% when the fraction of inspired oxygen was 49%. Moreover, the physical examination indicated diminished breath sounds on both sides and the accentuation of pulmonic second sounds.\nLaboratory data showed a high leukocyte count and an increased hemoglobin level, suggested abnormal liver biochemistry and hyperlipidemia, and revealed HHcy (24.12 µmol/L), high Vit B12 (734 µmol/L), and normal folate (14.39 nmol/L). The results of the protein S, protein C, anti-thrombin III antibody, anti-cardiolipin antibody, lupus anticoagulant, anti-β2gp1 autoantibody, and other autoantibodies were within normal limits. The clotting profile was normal, other than the D-dimer value (1.13 mg/L), and thrombophilia screening was negative. As markers in the risk stratification of PE, the levels of brain natriuretic peptide (BNP) and cardiac troponin I (CTnI) were 533 pg/mL and 0.334 ng/mL, respectively. Arterial blood gas levels measured with an oxygen concentration of 49% showed the following: pH, 7.44; PaCO2, 30 mmHg; and PaO2, 74 mmHg.\nAn electrocardiogram (ECG, Figure ) showed sinus tachycardia with typical changes on SIQIIITIII (S wave in the aVL lead, Q wave and T wave in the III lead). Ultrasonic cardiogram demonstrated right ventricular enlargement with left ventricular compression. Color Doppler scans were used to explore femoral, popliteal, and calf muscular venous thrombosis in the right extremity. Computed tomographic pulmonary angiography (CTPA) revealed occlusion of the pulmonary artery trunk, lobar artery, and arterial branches on both sides and signs of increased right heart load (Figure and ).