Solitary cyst of innominate

KENNETH P. HEIST, 0.0. Columbus, Ohio

The case reported here is of interest Solitary is an uncommon because of the unusual location of the benign cystic lesion of bone. It is still con- cyst, its size, and its treatment with sidered a disorder of unknown etiology al- though several theories have been proposed. heterogenous bone. The 15-year-old The cyst was first discovered in 1878 by Vir- male patient complained of hip pain chow, who reported on a case involving the after playing in a football game. humerus found at autopsy. It is a definite clini- He was admitted to the hospital after cal entity with well-defined features. x-rays showed a large lucent area in Unicameral bone cyst is a lesion of childhood and adolescence, usually occurring between the the left hip region. Examination ages of 4 and 21 years. The majority of the findings were within normal limits patients are between the ages of 10 and 15 except for slight tenderness on deep years. The male patient predominates two to palpation in the left gluteal region. one. Pelvic x-rays showed the lucent area The lesion is nearly always developed in the to measure about 12 by 10 cm. in the shaft of one of a few predilected long tubular . The proximal end of the humerus ac- left ilium, extending well into the counts for more than 50 per cent of the cases, sacroiliac articulating area. At surgery while over two thirds of them occur in the a large unicameral cavity was proximal humerus or femur. discovered with very thin connective Considering the fact that the skeleton makes tissue beneath a thin, distended up such a large percentage of the body and cortex. Ground cancellous bovine bone that the bone is so active a tissue, it seems peculiar that benign bone tumors are so un- was implanted in the cyst cavity. common. The pathologists report indicated the Coley stated that in a 37-year period, he lesion to be a benign solitary bone saw only 142 cases of solitary bone cyst in an cyst. Although the patient suffered active bone tumor clinic. Over half of the postoperatively from fever and serous cases occurred in the proximal end of the humerus and femur, with only one case found drainage, he responded well to in the ilium. antibiotic therapy with no apparent Neer and associates2 reported a total of 175 delay in healing. The graft was well cases of unicameral bone cysts, more than 50 tolerated and clinical and radiologic per cent of which occurred in the proximal examinations demonstrated satisfactory end of the humerus. In their series, solitary osseous union. The advantages of bone cysts of the ilium were rare. In the 175 cases, only three iliac cysts were found. The using processed heterogenous bone in ages of these three patients ranged from 33 to view of the patients age and the size 48. All three cysts were large and presented and location of the cyst are discussed. diagnostic problems. Biopsies were performed, but no treatment was administered, and, as the patients could not be followed up, the results

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are not known. temperature, and respiration were all within Jaffe and Lichtenstein3 from their own hos- normal ranges. pital records, over a period of 17 years, re- The patient demonstrated no evidence of ported no case in which a solitary unicameral muscular weakness, atrophy, or restriction of cyst appeared in other than long tubular bones. motion. The usual low-back and hip tests were The case reported here is of interest because negative while the pathologic reflexes were of the exceedingly rare occurrence of a solitary absent. The deep tendon reflexes were equal bone cyst in the innominate bone. and active bilaterally. Slight tenderness on deep palpation was present in the left gluteal Case report area, approximately 4 inches below the pos- A 15-year-old white male student was admitted terior iliac crest. The remainder of examina- with the chief complaint of left hip pain, which tion findings were essentially within normal had started approximately 3 weeks before and limits. could have been initiated by a tackle during a Results of laboratory tests were within nor- football game. The pain was sharp, of short mal limits, including serum and urinary cal- duration, and well localized, and was accentu- cium and phosphorus, alkaline and acid phos- ated by sitting, lying on the left side, and by phatase, total protein, lactic dehydrogenase, kicking with the right foot. C-reactive protein antiserum, latex fixation, Two weeks prior to his admission to the serum globulin and albumin, and blood urea hospital, the patient was seen by his family nitrogen. physician because of the hip pain. X-rays were On admission, x-ray of the pelvis revealed taken on the initial visit, but because of a pos- a large, lucent area measuring approximately sible profuse air pattern in the left hip area, 12 by 10 cm. in the left ilium, extending well he was instructed to return for additional into the sacroiliac articulating area. Radio- x-rays after complete evacuation of his bowel graphic differential diagnosis consisted of non- (Fig. 1). osteogenic fibroma, , and However, the large, lucent area remained in giant cell tumor. the left hip region, and so the patient entered On the patient's third hospital day, he was the orthopedic service of Doctors Hospital for taken to surgery for biopsy and curettage of additional studies. the cyst and possible packing of the cyst with The patient's personal history was essen- bone chips. During surgery, a large unicameral tially negative, with no known major illnesses, cavity was found with very thin connective surgery, or hospitalization, while the present tissue beneath a thin, distended cortex. After findings included chronic sinusitis, but no the cavity of the cyst was entered, thorough known heart, lung, or kidney diseases. curettage, irrigation with normal saline, and The family history was positive for diabetes, aspiration were performed. When the hetero- which involved his mother and older sister. genous bone was properly prepared, two bot- Physical examination upon admission to the tles of ground cancellous bone were loosely hospital revealed that he was an ambulatory, implanted, leaving the cavity underfilled rather young, muscular male in no apparent acute than overfilled. The cortex window from the distress. He was 6 feet 4 inches tall and opening was then replaced and the incision weighed 215 pounds. The blood pressure, pulse, closed in layers (Fig. 2).

312/116 Fig. 1 (left). X-ray reveals a lucent lesion involving a large portion of the left ilium and extending into the sacroiliac articulation area. Fig. 2 (right). Postoperatively, a large lucent area in the left ilium shows a mot- tled density throughout most of the area, a pattern incident to the heterogenous bone graft.

The surgical specimen was examined by the the culture showed pathologist, who reported the lesion to be a which was sensitive to Unipen. benign solitary bone cyst. Although the patient gradually became afe- Approximately 12 hours after surgery, the brile, large amounts of drainage material con- patient developed hyperpyrexia, his tempera- tinued to come from the surgical site. Gradu- ture ranging from 100 to 103 degrees, and ally the drainage subsided and on the patients antibiotic therapy was begun immediately. Cul- fifteenth hospital day and his twelfth post- ture of the urine revealed no growth, while the operative day he was afebrile and left the white blood cell count was 12,000. Although hospital on crutches. He was discharged to the the surgical site remained dry and the labo- care of his family physician and was to be seen ratory results were within normal limits, the as an outpatient by the orthopedic department. patient retained a low-grade fever for several He was seen periodically, at which times days. However, on the seventh postoperative x-rays were taken (Figs. 3-6). Healing was sat- day, drainage appeared at the surgical site and isfactory, without fever or drainage. Approxi-

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Fig. 3 (left). View 1 month after operation shows relatively lucent zone in its peripheral portion. Fig. 4 (right). At 3 months lucent zone in upper portion of graft is absent and graft is less dense and confluent.

mately 4 weeks after surgery, the patient was capable of full weight bearing without discom- fort. Throughout his postoperative visits, the x-rays continued to appear normal, and ap- proximately 1 year after surgery the patient was discharged as asymptomatic. A check-up x-ray examination made 2 years postoperatively showed additional filling in with compact bone (Fig. 7).

Discussion As the name implies, the solitary unicameral bone cyst is limited to a single location in one bone. It is a slowly growing, benign, cystic lesion of bone and is the only purely cystic Fig. 5. Nine months postoperatively cystic area ap- bone lesion. Although it is not a tumor, it is pears stable and the pelvis has an otherwise satis- often conveniently classified as a tumor be- factory appearance.

314/118 Fig. 6 (left). X-ray made 1 year postoperatively shows adequate regeneration and viability of the architecture in the area. Fig. 7 (right). At 2 years size of the cavity has reduced appreciably and there is some sclerotic margin, which represents additional filling in with compact bone.

cause of its clinical similarity to the bone Anatomically, the lesion presents itself as a tumors. cyst-like cavity filled with amber-colored or The cyst is usually of moderate or large size blood-stained fluid. The cortical bone overlying before its presence is discovered. In about half the cyst is usually extremely thin and fragile. the patients, the cyst is not discovered until a Although the cyst is unilocular, its walls may be pathologic fracture has occurred. Although transversed by marrow of bone. The cavity is pain is the most common complaint, swelling usually lined by a delicate, thin, connective tis- is usually not a prominent symptom. In approx- sue membrane, yielding, as a rule, little mate- imately two thirds of the cases, there is a his- rial to curettage. Microscopically, the material tory of trauma, and it is then that attention is is found to be mainly fibrin clots, often con- drawn to the lesion because of the pathologic taining some red blood cells and undergoing fracture. Over one third of the patients seek organization. treatment within 1 week of the onset of the Roentgenographically, unicameral bone cysts symptoms, whereas, without a fracture, the usually present a multilocular bone defect and duration of symptoms from onset to treatment are characterized by a circumscribed outline, a is 2 years. thinning of the cortex without expansion, and

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absence of bone trabeculation within its border union was demonstrated both clinically and except in instances where a pathologic frac- radiologically. ture has occurred. Since the cysts usually occur in the shafts of Summary the long bones of younger individuals, they are Solitary bone cyst in itself is an unusual clini- generally located at the lying jux- cal entity, but when it occurs in the innominate taposed to the epiphyseal plate, and they rarely, bone it must be considered a rare finding. The if ever, transgress the plate. case presentation is of interest because of the Usually, differential diagnosis of a solitary location of the cyst, its size, and its treatment bone cyst is not difficult, but clinical entities by implantation of sterile processed bovine which may present a diagnostic problem in- bone (Boplant). clude fibrous dysplasia, aneurysmal bone cysts, Brodies , benign giant cell tumor, osteo- sarcoma, and hemangioma. There is still some disagreement as to when 1. Coley, B. L.: Neoplasms of bone and related conditions; etiology, pathogenesis, diagnosis and treatment. Ed. 2. Paul B. a solitary bone cyst should be operated upon, Hoeber, Inc., Medical Division of Harper Brothers, New York. and whether the stage of the bone cyst or its 1960 2. Neer, C. S., II, et al.: Treatment of unicameral bone cyst. location is of any importance. Treatment of the A follow-up study of one hundred seventy-five cases. J Bone bone cyst usually consists of curettage of the Joint Surg [Amer] 48-A:731-45, Jun 66 3. Jaffe, H. L., and Lichtenstein, L.: Solitary unicameral bone membranous lining and filling the cystic cav- cyst, with emphasis on the roentgen picture, the pathologic ity with chips or strips of autogenous bone. appearance and the pathogenesis. Arch Surg 44:1004-25, Jun 42 Aegerter, E., and Kirkpatrick, J. A., Jr.: Orthopedic diseases. In this case, because of the size and location of Physiology, pathology, radiology. Ed. 2. W. B. Saunders Co.. the lesion, accurate diagnosis and prompt sur- Philadelphia, 1964 Anderson, K. J., Le Cocq, J. F., and Mooney, J. G.: Clinical gery were indicated. For several reasons, proc- evaluation of processed heterogenous bone transplants: A pre- essed, heterogenous bone was ideal. Because of liminary study. Clin Orthop 29:248-63, 1963 Anderson, W. A. D.: Pathology. Ed. 2. C. V. Mosby Co., St. the patients age, it eliminated both an un- Louis, 1953 sightly donor-site scar and possible disturbance Crenshaw, A. H., Ed.: Campbells operative orthopedics. Ed. 4. of the epiphysis at the donor site. The enor- C. V. Mosby Co., St. Louis, 1963, vol. 2 Meschan, I.: Ro^atgen signs in clinical diagnosis. W. B. Saunders mous size of the cyst itself all but eliminated Co., Philadelphia, 1956 Sante, L. R.: Principles of roentgenological interpretation. Ed. the use of an autogenous graft. The location of IL Edwards Brothers, Inc., Ann Arbor, Michigan, 1958 the lesion made for accessible exposure and Tumors of bone and soft tissue. A collection of papers presented at the Eighth Annual Clinical Conference on Cancer, 1963, at convenient use of surgibone. The use of heter- the University of Texas M. D. Anderson Hospital and Tumor ogenous bone also provided availability and Institute, Houston, Texas. Year Book Medical Publishers, Inc., Chicago, 1965 variety of adequate quantities of required bone and eliminated the need for a donor-site operation and additional preparation. One of the primary complications of bone This paper was written during Dr. Heists residency in the grafting is infection, and, although serous Department of Surgery, Division of Orthopedic and Traumatic Surgery, Doctors Hospital, Columbus, Ohio, of which Dr. Harold drainage was present in this case, the drainage E. Clybourne is chairman. It was presented at the Thirty-Ninth responded well to antibiotic treatment and no Annual Clinical Assembly of the American Osteopathic Academy of Orthopedics, Washington, D. C., October 25, 1966. apparent delay in healing was noted. The graft Dr. Heist, Doctors Hospital, 1087 Dennison Avenue, Columbus, was well tolerated and satisfactory osseous Ohio 93201.

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