S. aureus is still the most common pathogen in acute knee infections in our environment. Gram staining, absence of fever and normal leukocyte count cannot be used to rule out septic arthritis.

No abstract

A 55-year-old overweight woman with a history of endometrioid carcinoma, gastric bypass, hysterectomy and bilateral salpingooophorectomy, removed breasts fibroadenoma, secondary osteoporosis and T12 vertebrae pathological fracture, presented to the emergency department with a 9 days history of holocranial headache, fatigue and generalized myalgias after the administration of 5 mg zoledronic acid (ZA) for her osteoporosis treatment. Despite paracetamol management, pain in the inferior extremities exacerbated, limiting her gait. Physical examination revealed edema and erythematous nodules on both inferior extremities, painful to touch, of an average 10 mm diameter (Figure 1A,B). The rest of the physical exam was normal.Chronic medications taken by the patient were 1500 mg calcium citrate +2200 IU vitamin D daily, vitamin B 12 applied monthly and 60 mg denosumab application every 6 months. Initial imaging and laboratory studies revealed a lower extremities Doppler ultrasound negative for deep vein thrombosis, a normal chest X-ray, a normal blood count, a mild elevation of erythrocyte sedimentation rate (38 mm/h) and C-reactive protein (0.694 mg/dL). Renal function was preserved (blood urea nitrogen and creatinine 11 mg/dL and 0.52 mg/dL respectively), ionic calcium level was on the lower range limit. No other abnormalities on initial tests were found.An erythema nodosum (EN) diagnosis was made, possibly due to a drug-related reaction given the temporal administration of ZA and the denosumab chronic use (Table 1). The patient was started on salicylic acid 500 mg three times a day, paracetamol and tramadol 1000 mg and 50 mg three times a day, respectively, and physical rest was recommended for management of EN. A punch biopsy showed fibroconnective tissue thickening on the septae separating fat lobules and intramural calcium deposit on subcutaneous tissue blood vessels (Figure 2A), which was confirmed by a Von Kossa stain (Figure 2B).Due to the incidental histopathologic finding of calciphylaxis, more tests were performed, including kidney and liver functions, infectious diseases, immunological and endocrinological tests as well.A mild vitamin D deficiency (calciferol 20.6 mg/dL, reference levels 30-40 ng/mL), hypocalcemia (total serum calcium 7.8 mg/dL, reference range 8.8-10.6 mg/dL), ionic calcium (1.1 mmol/L, reference 1.16-1.32 mmol/L) and 24-hour severe hypocalciuria (12.5 mg/24 h, reference 100-300 mg/24 h) were found. No other laboratory abnormalities were documented.

El eccema numular es una dermatosis crónica y recidivante que se manifiesta con placas en forma de moneda, pruriginosas, de tamaño variable y bordes definidos, que evolucionan a placas liquenificadas y con descamación. A pesar de que se considera una enfermedad de adultos, existen reportes de caso de niños con ec­cema numular. Afecta a ambos sexos y las lesiones se presentan con mayor fre­cuencia en las extremidades, aunque pueden comprometer el tronco y el rostro. La etiología de esta entidad es desconocida. Se considera una enfermedad mul­tifactorial en la que intervienen fármacos, infecciones, alérgenos, irritantes, fac­tores ambientales y factores emocionales, entre otros. Dado que la histopatología es inespecífica, el diagnóstico es eminentemente clínico. Los tratamientos farmacológicos más usados y reportados involucran corticoides tópicos de mediana y gran potencia, asociados a emolientes y antihistamínicos. Sin embargo, hay reportes de casos en los que se han usado inmunomoduladores e inmunosupresores, especialmente en los casos graves y de difícil manejo.