Thrombocytopenia-Absent Radius Syndrome (TAR)

A. Kritter, M.D. B. Myers, M.D. G. Thatcher, M.D.


A patient seen at the Juvenile Amputee Clinic of the Milwaukee Children's Hospital has drawn the attention of the authors to the association of a hematological problem-thrombocytopenia-with bilateral absence of the radii. This syndrome has also been known as a Radius-Platelet Hypoplasia or RPH and is now called TAR (Thrombocytopenia-Absent Radius Syndrome).7

Case: R.J.

Born on Feb. 20, 1969, this boy was referred to the Juvenile Amputee Clinic at the age of 2 1/2 months. The chief complaint was deformity of both upper extremities. The mother's pregnancy had been uneventful and the child's birth weight was 8 lb., 6 oz. Two older siblings had been treated for bilateral tibial torsion but there was no family history of upper-extremity anomalies.

Physical examination revealed a child with bilateral absent radii, short curved ulnae, with the defect more severe on the right limb, and curved fifth fingers with short middle phalanges. Examination of the skin did not yield any unusual findings, and no bruises were present. The physical examination did not reveal any other skeletal deformities (Fig. 1 and Figs. 2 and 3 ).

X-rays of both upper extremities taken on May 14, 1969, showed both humeri to be of normal length but the bone on the left side was thinner than the one on the right. The radii were absent bilaterally with shortening of both ulnae which was more severe on the right side than on the left. The middle phalanges of both fifth fingers were short and these fingers pointed laterally. Examination of the soft tissues of the upper extremities revealed nothing remarkable nor did AP and lateral x-rays of the chest (Fig. 4 and Fig. 5 ).

Initially the child's anomalies were thought to be routine bilateral congenital absences of the radii and he was placed in functional ulnar splints to begin stretching the soft tissues in order to reposition the hand for anticipated surgical correction later in life.

The child was seen at the next Clinic meeting to evaluate the newly applied ulnar splints. By that time Dr. Myers had joined the staff of the Amputee Clinic and on examining the child she raised the question as to the possibility of a thrombocytopenia being present.

Thus, when the child was five months old, blood studies were performed and revealed a hemoglobin of 10.3 ms/100 ml., hematocrit 30%, WBC 13,800 with 42% neutrophils, 42% lymphocytes, 5% monocytes, 8% easinophils, and 3% basophils. Few platelets were seen on smear. Platelet count has remained between 4,000 and 26,000 per cubic millimeter. This information confirmed the suspicion that a thrombocytopenia was present although no clinical manifestations of the condition were evident at this time.

KUB (kidney, urinary tract, bladder) film and an excretory urogram done on July 9, 1969, showed the kidneys to be within normal limits in size, shape, and position. They concentrated contrast satisfactorily, and the calyces, pelves, ureters, and bladder were adequately seen and were normal.

The indication of thrombocytopenia altered the plan for eventual surgical correction of the malformed hands and pointed out the precarious prognosis for life.

The child was seen again in November 1969, at which time the first evidence of ecchymosis was noted in the glabellar area. The mother had also noticed hematomas about the lower central incisors which were erupting normally. The child's platelet count was less than 4,000. The splints were changed, and the patient was again seen in February 1970. At that time the mother reported the child had had a bleeding episode which had continued for more than two hours after a fall had caused a minor laceration of the buccal mucosa.

The child was continued in the splints with gratifying response as far as the positioning of the hands was concerned. However, death occurred in August 1970. An autopsy was not obtained, and the cause of death was reported as gastroenteritis and septicemia. It could not be definitely determined whether a fatal bleeding episode had been the precipitating cause of death.

Discussion

Several authors1-8 have noted the association of thrombocytopenia with bilateral radial aplasia. The bone abnormalities have consistently been bilateral absence of the radii with some hypoplasia of the ulnae and sometimes of the humeri. Rarely is the deformity unilateral. The cause is unknown, but evidence of a genetic etiology is supported by the occurrence of the syndrome in several sets of siblings6.

Hematologically, a thrombocytopenia can be detected within the first few months of life but usually no anemia is noted unless there has been a loss of blood. A leukemoid reaction is frequently observed. Bone marrow studies usually reveal a deficiency of megakaryocytes with a cellular marrow. The major symptom is easy bruising of the skin, although several children have been reported to have died of hemorrhages, especially cerebral. Prognosis is guarded as 40% of the patients die in the first year of life. However, the prognosis improves if a child survives the first year.

Several treatments have been advocated for severe bleeding episodes. These include platelet transfusions, splenectomy, and corticosteroid treatment. The value of these treatments in altering the overall course of the disorder is doubtful.

This syndrome is well differentiated from Fanconi's anemia as is illustrated in Table 1 taken from the article by Temtamy and McKusick7. Thus, this syndrome of bilateral absent radii with thrombocytopenia is a separate entity.

The purpose of this case report is to call this syndrome to the attention of readers of the Inter-Clinic Information Bulletin as it is likely to appear in an amputee or limb-deficiency center. The experience also strikingly points out the advantages of having a pediatrician as a member of the Juvenile Amputee Clinic team.

Juvenile Amputee Clinic, Children's Hospital Milwaukee, Wisconsin; A. Kritter is Director

B. Myers is Medical Coordinator, Birth Defects Center

G. Thatcher is Pediatric Hematologist

References:
1. Bayrakei, D., and John R. Walsh, Amegakaryocytic thrombocytopenia and bilateral absence of the radii. Postgraduate Med., 33:401, 1963. 
2. Classen, M. A., Congenital thrombocytopenia with aplasia of the radii, Nebraska Med. J., 49:419, 1964. 
3. Dignan, P., and A.M. Mauer, A new syndrome associating skeletal deformities and blood cell abnormalities, J. Ped., 67:725, 1965. 
4. Emery, J. D., R. R. Gordon, J. Rendle-Short, S. Varadi, and A. J. Warrach, Congenital amegakaryocytic thrombocytopenia with congenital deformities and a leukemoid blood picture in the newborn, Blood, 12:567, 1957. 
5. Nilsson, L. R., and G. Lundholm, Congenital thrombocytopenia associated with aplasia of the radius, Acta Pediat., 49:291, 1960. 
6. Shaw, S., and R. A. M. Oliver, Congenital hypoplastic thrombocytopenia with skeletal deformities in siblings, Blood, 14:374, 1959. 
7. Temtamy, Samia, and Victor A. McKusick, Synopsis of hand malformations with particular emphasis on genetic factors, Birth Defects: Original Article Series, Vol. V, No. 3:194, 1969. 
8. Zetterstrom, R., and B. Strindberg, Sporadic congenital spherocytosis associated with congenital hypoplastic thrombocytopenia and malformations, Acta Pediat., 47:14, 1958.