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The management of acute scrotum can be challenging, especially in infants or patients with a neurological or neurodevelopmental disorder in whom presentation, diagnosis and definitive management tends to be delayed. This leads to poor outcomes, such as loss of the affected testis. Here we present two cases of testicular torsion in patients with neurodevelopmental disorders, and a further two cases of epidydimo-orchitis in whom measurement of CD64 expression on neutrophils was helpful for differential diagnosis. These data suggest that the levels of expression of CD64 by neutrophils, known as a marker of infection, could also be useful for differentiating between testicular torsion and infection in acute scrotum., (© 2015 The Japanese Urological Association.)

Objective: To evaluate the utility of quantifying CD64 expression on neutrophils in rheumatoid arthritis patients with malignancy, especially its diagnostic role in lymphoma., Methods: We used flow cytometry to quantify CD64 expression on neutrophils from patients diagnosed with malignancy during the follow-up period prior to initiating treatment., Results: Neutrophils from 18 patients with lymphoma expressed significantly higher levels of CD64 (9635.6 ± 2123.7 molecules/cell) than those from 32 patients with other solid cancers (carcinoma) (1250.5 ± 91.1 molecules/cell) (p < 0.001). When the cutoff value was set at 2060 molecules/cell, the sensitivity and specificity of CD64 for diagnosing lymphoma was 88.9% and 94.4%, respectively., Conclusions: The quantitative measurement of neutrophil CD64 by flow cytometry may be useful as a subsidiary diagnostic marker in patients with suspected lymphoma. Although neutrophil CD64 is currently a well-known marker of infection, it is necessary to bear in mind that lymphoma is also a candidate in differential diagnosis when CD64 expression on neutrophils is upregulated.

Objective: To evaluate the utility of neutrophil CD64 as a marker for monitoring the activity of nontuberculous mycobacteria (NTM) infection in patients with rheumatoid arthritis (RA)., Methods: We compared neutrophil CD64 expression in nine RA patients with NTM infection in the active and inactive phase of NTM disease chronologically. "Active phase" was here defined as present in patients admitted to hospital to receive intensive treatment for NTM, as well as outpatients with an infectious episode showing positive acid- and alcohol-fast bacillus (AFB) staining of sputa (Grade 2-3) who needed to start treatment for NTM with a multiple antibiotics regimen. The cut-off value for CD64 positivity was 2000 molecules/cell., Results: Neutrophils from patients with active-phase NTM infection expressed high levels of CD64 with a mean ± SEM of 7335 ± 784 molecules/cell. However, during the inactive phase of disease, this was significantly lower (1481 ± 103 molecules/cell, p < 0.001). The sensitivity and specificity of neutrophil CD64 to detect active-phase NTM infection was 96.3% and 84.6%, respectively. Expression of neutrophil CD64 was not affected by disease activity of the RA itself., Conclusions: Neutrophil CD64 is useful for monitoring disease activity in NTM infection of patients with RA.

The usefulness of neutrophil CD64 expression was examined in diagnosing local infection, including soft tissue, bone, and joint infections. Among 99 patients suspected of local infection, 31 were confirmed and 68 patients were not. The CD64 level of patients with local infection was significantly higher than in those without infection [4,193 ± 1,132 vs. 1,017 ± 59 molecules/cell (mean ± standard deviation); p < 0.001]. The area under the curve of CD64 calculated by receiver operating characteristic curve analysis was larger than that of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), or white blood cell (WBC) count. In addition, CD64 levels of patients with crystal-induced arthritis remained within cutoff value (2,000 molecules/cell). These data suggest that measuring CD64 expression can be a useful diagnostic marker for local musculoskeletal infection and crystal-induced arthritis.

Background: The diagnosis of local infection in patients with rheumatoid arthritis (RA) is frequently difficult because clinical signs and symptoms and laboratory test results of local infection are also observed in arthritis of active RA. The need for a specific marker of infection is high in RA patients. The usefulness of neutrophil CD64 expression (CD64) to diagnose local musculoskeletal infection (local infection) and discriminate local infection from RA-related inflammation in RA patients was examined., Methods: CD64 was measured by a quantitative method using flow cytometry in 61 RA patients in whom local infection was suspected, and the usefulness of CD64 was examined by comparing the findings with clinical results., Results: There were 25 patients with local infection and 36 patients without infection. The median CD64 value the patients with local infection was 3148 molecules/cell (interquartile range [IQR], 2140-6231) and that of the patients without infection was 1106 molecules/cell (IQR, 804-1464) with a statistically significant difference (P < 0.0001). In contrast, no significant difference between the groups was observed in C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count. The area under the curve of CD64 calculated by receiver operating characteristic curve analysis was larger than that of CRP, ESR, or WBC count, suggesting that CD64 has superior ability to discriminate of infection compared to these other markers. When the cutoff value of CD64 was set at 2000 molecules/cell, the sensitivity and specificity of CD64 for the detection of local infection in RA patients were 76.0% and 94.4%, respectively., Conclusions: CD64 is a useful marker in RA patients to discriminate local infection from RA-related inflammation.

We examined the usefulness of neutrophil CD64 expression in detecting local musculoskeletal infection and the impact of antibiotics on its expression. Of 141 patients suspected of musculoskeletal infection, 46 were confirmed by microbiological culture to be infected and 95 had infection excluded. The median CD64 count of patients with localised infection was 2230 molecules per cell (interquartile range (IQR) 918 to 4592) and that of the patients without infection was 937 molecules per cell (IQR 648 to 1309) (p < 0.001). The level of CD64 correlated with the CRP level in patients with infection, but not in those without infection (r = 0.59, p < 0.01). Receiver operator characteristic curve analysis revealed that CD64 was a good predictor of local infection. When the patients were subdivided into two groups based on the administration of antibiotics at the time of CD64 sampling, the sensitivity for detecting infection was better in those who had not received antibiotics. These results suggest that measurement of CD64 expression is a useful marker for local musculoskeletal infection.

Objective: In inflammatory diseases, differentiation between infection and disease flares is often clinically difficult because of similar signs and symptoms, such as fever and elevation of inflammatory markers. In rheumatoid arthritis (RA), infection is not only one of the major complications but also one of the frequent causes of death. Use of biologic agents such as tumor necrosis factor-a blockers has been reported to increase the incidence of tuberculosis or opportunistic infections. We examined the utility of CD64 (FcgRI) expressed on neutrophils as a marker for detection of infection complicated with RA., Methods: We measured the expression level of CD64 per neutrophil quantitatively by flow cytometry in 279 samples from 237 patients with RA with various levels of disease activity or types of infection, and in 52 samples from 36 controls including subjects with infection., Results: CD64 expression was significantly higher among RA patients with infection (median 4156 molecules per neutrophil, interquartile range 2583-8587) than in those without infection (884, IQR 670-1262) (p < or = 0.001). The sensitivity of CD64 on neutrophils for the diagnosis of infection (using a cutoff value of 2000 molecules per cell) was 92.7% and specificity was 96.5%. CD64 expression was not affected by the disease activity of RA or the use of corticosteroids, disease modifying antirheumatic drugs, and biologic agents. CD64 was upregulated in infection by bacteria, viruses, fungi, and mycobacteria., Conclusion: Our results suggest that quantitative measurement of CD64 expression on neutrophils can be used as a sensitive and specific marker to detect infection complicating RA.