Excess water diuresis can develop during treatment of chronic hyponatremia caused by psychogenic polydipsia, often resulting in overcorrection of the serum sodium level, leading to irreversible damage of the central nervous system. We report the case of a patient with severe chronic hyponatremia whose serum sodium level was successfully corrected by continuous infusion of low-dose vasopressin. The patient was a 64-year-old man who had a history of treatment for schizophrenia and psychogenic polydipsia. He was brought to the ER of our hospital by ambulance due to consciousness disturbance, and his serum sodium level was 102 mEq/L. His condition was complicated by bacterial pneumonia and rhabdomyolysis. After admission to the intensive care unit, he excreted a large amount of diluted urine, resulting in intravascular volume depletion and a rapid increase in the serum sodium level associated with intractable hypotension. We then initiated continuous infusion of vasopressin at a dose of 0.25 units per hour, resulting in increased urine osmolality, reduction of the urine volume, and resolution of hypotension. Thereafter, the serum sodium level normalized at an appropriate rate of correction. We suggest that in cases of severe chronic hyponatremia, continuous infusion of low-dose vasopressin can prevent overcorrection of the serum sodium level, particularly in cases associated with infectious complications.

Penicillins may cause hypokalemic metabolic acidosis. On the other hand, it has been reported that the simultaneous use of penicillins and acetaminophen may cause the accumulation of pyroglutamic acid (PGA; also known as 5-oxoproline), thereby leading to the development of high anion gap metabolic acidosis (HAGMA). We report a case of HAGMA that was considered to be caused by penicillin G (PCG) alone. A 59-year-old man presented with severe pain, swelling, and redness of his left leg. He was diagnosed with necrotizing fasciitis associated with septic shock syndrome, which was caused by Streptococcus pyogenes. He immediately underwent excisional debridement of the affected tissues, and was treated using high-dose PCG, clindamycin, corticosteroid, and γ globulins. As his condition was complicated by acute kidney failure, we initiated continuous hemodiafiltration (CHDF). On the 5th day of admission, his kidney function recovered and CHDF was withdrawn. Paradoxically, he thereafter developed rapidly-worsening HAGMA, requiring daily hemodialysis to treat severe acidosis. He had no ketoacidosis, lactic acidosis, or exposure to toxic agents. On the 11th day of admission, as accumulation of PGA induced by PCG was suspected, we withdrew all antibiotics except for clindamycin, resulting in the gradual resolution of HAGMA. This case suggests that HAGMA can be caused by PCG alone and withdrawal of causative drugs should be considered whenever this condition is suspected.

Neuroendocrine tumors of the uterine cervix have a poor prognosis, and lead to lymph node and distant metastases even at an early stage. Due to the rarity of these tumors (1 to 2% of cervical invasive cancers), it is difficult to construct therapeutic strategies based on prospective clinical trials. Cervical adenocarcinoma also has a poorer prognosis than squamous cell carcinoma, and there is limited evidence for a therapeutic approach. In this report, we present the case of a patient with stage IB2 cervical cancer, which consisted of both adenocarcinoma and neuroendocrine tumor elements. The patient underwent radical hysterectomy following 2 cycles of paclitaxel and carboplatin (TC) therapy as neoadjuvant chemotherapy. A 38-year-old woman, gravida 2, parity 2, with no noteworthy past or family history, presented with a 2-month history of increased mucous discharge with abnormal odor. The entire cervix was swollen and malignant lesions were observed in the anterior vaginal fornix and in the 5 o'clock direction in the cervix. Tissue biopsy of the former lesion showed endocervical adenocarcinoma, usual type with an abnormal tubular or papillary structure, while the latter lesion showed sheet-like to alveolar growth of strongly atypical cells, indicating it to be large cell neuroendocrine carcinoma. On pelvic contrast-enhanced MRI, two masses with different internal properties, contrast effects, and diffusion capacity were present next to each other. Contrast-enhanced CT of the chest to the pelvis demonstrated no swelling of the lymph nodes or distant metastases, but the tumor markers CEA (13.2 ng/mL) and CA19-9 (61.5 U/mL) had high values. Based on the diagnosis of stage IB2 cervical cancer, neoadjuvant chemotherapy was performed during the surgical waiting period. She received 2 cycles of TC therapy, and the tumor significantly decreased in size. Radical hysterectomy was performed, and histopathological examination of the removed uterus revealed the coexistence of CD56(+) and synaptophysin(+) components corresponding to neuroendocrine/atypical carcinoid tumors in the adenocarcinoma dominant lesions, some of which had migrated to each other. According to the 4th edition of the General Basis for Clinical and Pathological Management of Uterine Cervical Cancer, Pathological Edition, published in 2017, her tumor was classified into the adenocarcinoma admixed with neuroendocrine carcinoma category. The postoperative course was uneventful and additional 4 cycles of TC therapy were performed. There is a report that neoadjuvant chemotherapy for uterine cervical cancer may prolong survival. On the other hand, effective chemotherapy for cervical neuroendocrine tumors has not yet been established. This case suggests that TC therapy is effective not only as a neoadjuvant chemotherapy but also for cervical neuroendocrine tumors.