Difficulties in Immunohaematology : The Weak D Antigen

Background

The Rh blood system is one of the most polymorphic and immunogenic systems known to humans. The expression of Rh blood group antigen is complex. The Rh D antigen is the most important of the antigens that constitute the Rh antigen system. In most cases, D antigen can easily be detected. However, due to variability of expression, weak forms antigen are encountered. The reactivity of weak D with antisera is variable and presents as a problem in blood banking.

Methods

A retrospective analysis for a five-year period was done. Blood samples that were negative for Rh D by immediate spin tube method were tested for weak D antigen by additional lab tests.

Result

Of 34932 serial Rh grouping tests done in our Blood Bank, the incidence of weak D Rh antigen was 0.189%. All these were confirmed by the antiglobulin test.

Conclusion

These patients present as a problem for the blood banker and a curiosity to the clinician. Although uncommon, all health care workers should be aware of this entity to avoid anti D alloimmunisation.Key Words: Weak D, Rh Blood Group     

Role of prophylactic intravitreal antibiotics in open globe injuries

PURPOSE: To determine the efficacy of prophylactic intravitreal antibiotics in reducing the incidence of endophthalmitis after trauma. METHODS: This was a prospective, randomised, case control study of 70 consecutive patients with open globe injury. The patients were prospectively randomised into group I (32 eyes) and group II (38 eyes). Group I patients were given prophylactic intravitreal injection of vancomycin 1 mg and ceftazidime 2.25 mg at the conclusion of primary repair. Group II patients were not given prophylactic intravitreal antibiotics. All the patients received intravenous ciprofloxacin. RESULTS: The incidence of endophthalmitis was higher in group II (7 of 38 eyes; 18.42%) compared to group I (2 of 32 eyes; 6.25%). Both the patients who developed endophthalmitis despite prophylactic intravitreal antibiotics in group I had an initially undetected intraocular foreign body (eyelash) in the vitreous cavity. CONCLUSIONS: Prophylactic intravitreal broad spectrum antibiotic injection decreases the risk of post-traumatic endophthalmitis.     

Postoperative complications and visual results in uniocular pediatric traumatic cataract

BACKGROUND AND OBJECTIVES: This study was prospectively carried out to evaluate the postoperative complications and visual results following posterior chamber intraocular lens (PCIOL) implantation in children with unilateral traumatic cataract. PATIENTS AND METHODS: We prospectively evaluated 40 children, 12 years or younger, with traumatic cataract (blunt trauma, n = 22 eyes, repaired penetrating eye injury, n = 18 eyes) undergoing PCIOL implantation with a minimum follow-up period of one year. Children with posterior segment ocular injury were excluded. RESULTS: The postoperative complications were significantly higher in the penetrating eye injury group as compared to blunt trauma group (ie, pupillary capture 44.44% vs 9.09%, posterior capsulotomy rate 83.33% vs 40.90% and IOL decentration 27.77% vs 4.54%). The final visual acuity was 6/12 or better in 38.8% and 86.36% of eyes with penetrating eye injury and blunt trauma, respectively. CONCLUSION: Extracapsular cataract extraction (ECCE) with PCIOL implantation in traumatic cataract following blunt trauma results in better visual outcome and fewer complications compared to penetrating eye injury if the posterior segment is not involved.     

Primary retroperitoneal myxoid/round cell liposarcoma is a nonexisting disease: an immunohistochemical and molecular biological analysis

Almost all primary retroperitoneal liposarcomas can be classified as well-/dedifferentiated liposarcoma. Rarely, however, primary retroperitoneal liposarcoma is classified as myxoid/round cell liposarcoma, based on the presence of myxoid areas and vascular crow's feet pattern, which has resulted in a debate on the classification of liposarcoma in the retroperitoneum. Genetically, myxoid/round cell liposarcoma and well-/dedifferentiated liposarcoma are different diseases. Myxoid/round cell liposarcoma is characterized by a translocation causing FUS-CHOP or EWSR1-CHOP fusion, whereas well-/dedifferentiated liposarcoma is characterized by an amplification of the 12q13-15 region, including MDM2 and CDK4 genes. As myxoid/round cell liposarcoma is highly radio- and chemosensitive, differentiation between subtypes is important to optimize treatment. We studied whether primary retroperitoneal liposarcomas diagnosed as myxoid/round cell liposarcoma represent molecularly true myxoid/round cell liposarcoma or are histopathological mimics and represent well-/dedifferentiated liposarcoma. Primary retroperitoneal myxoid/round cell liposarcoma (n=16) were compared to primary extremity myxoid/round cell liposarcoma (n=20). Histopathological and immunohistochemical features were studied. Amplification status of the 12q13-15 region was studied using a multiplex ligation-dependent probe amplification analysis, and FUS-CHOP or EWS-CHOP translocations were studied using RT-PCR. In primary retroperitoneal myxoid/round cell liposarcoma, MDM2 and CDK4 staining was both positive in 12 of 15 cases. In primary extremity myxoid/round cell liposarcoma, MDM2 was negative in 18/20 and CDK4 was negative in all cases. Multiplex ligation-dependent probe amplification showed the amplification of 12q13-15 region in 16/16 primary retroperitoneal myxoid/round cell liposarcomas and in 1/20 primary extremity myxoid/round cell liposarcomas. Translocation was present in all (18/18) primary extremity myxoid/round cell liposarcomas, but absent in all primary retroperitoneal myxoid/round cell liposarcomas. On the basis of immunohistochemical and molecular characteristics, apparent primary retroperitoneal myxoid/round cell liposarcoma can be recognized as well-/dedifferentiated liposarcoma with morphological features mimicking myxoid/round cell liposarcoma. In these cases, treatment should probably be specifically designed as for well-/dedifferentiated liposarcoma. Moreover, finding of myxoid/round cell liposarcoma translocations in a retroperitoneal localization is highly suggestive of metastasis and should prompt search for a primary localization outside the retroperitoneum.