Secondary Aneurysmal Bone Cyst of Base of Skull Associated with Chondroblastoma

Abstract

Sir,Aneurysmal bone cysts (ABCs) are multi-cystic, osteolytic growths. The classic or standard form (95%) has blood filled spaces among bony trabeculae. Osteoid tissue and osteoclastic giant cells are found in the stromal tissue. The solid form (5%) shows fibroblastic proliferation, osteoid production and degenerated calcifying fibromyxoid elements. 1 ABCs are usually seen in younger patients. Around 80% of the patients are less than 20 years of age, more frequently in females. ABCs occurring de novo are called as primary ABCs. Secondary ABCs have accompanying tumors like chondroblastoma and giant cell tumor in 30% of patients. Other associated tumors or non-tumorous conditions include ossifying fibroma, osteosarcoma, chondrosarcoma, non-ossifying fibroma, chondromyxoid fibroma, unicameral or solitary bone cyst or trauma. 2 ABCs are commonly found in long bones, membranous bones of the thorax, pelvis and vertebra. In long tubular bones, these tend to be eccentrically located in the metaphysis. However, these can occur in any location, including the diaphysis and epiphysis, rarely, involving multiple bones simultaneously. 3 Skull is rarely affected. 4,5 The treatment modalities include selective arterial embolization, irradiation, intralesional curettage, intraoperative adjuvants, bone grafting, marginal resection or wide excision. Tumor has to be excised and all cystic lining curetted. Cryotherapy, phenol or cauterizations (intraoperative adjuvants) are used to remove microscopic tumor cells. Resulting bony defects may be replaced with homologous bone or cadaveric bone. We, herein, present a 50-year patient who was admitted with the complaints of headache, and rapidly enlarging swelling in the right temporal and mastoid area elevating the auricle. There was serosanguinous ear discharge and loss of hearing from right ear. There was no history of trauma. Swelling was non-tender, firm to hard and pulsatile. Cough impulse was negative and no bruit was audible. Right seventh nerve was paralysed with lower motor neuron features. No other body part was involved. CT scan brain with contrast and CT-angio brain revealed a vascular mass with bony outgrowth and cystic spaces involving right temporal petrous and mastoid area with midline brain shift (Figure 1). Patient underwent operation and lesion was excised and surrounding bony area was cauterised. Attached dura was coagulated with bipolar diathermy. Histopathology report confirmed the diagnosis of chondroblastoma with secondary ABC. Patient remained well for one year, however, he had recurrence of same growth after one year. Second operation was performed in the same way. He was then referred for radiotherapy. This case is unique as it presented at advanced age and in an unusual location. As mentioned above, skull is very rarely the primary site for this lesion. Both the primary tumour and the associated secondary ABC are rare at this age. Moreover, this case recurred after one year. Recurrence is not rare in ABCs. Most commonly, it results from incomplete removal of the...

Isolated calvarial aneurysmal bone cyst in a pediatric patient: illustrative case

“…Approximately 30% of calvarial ABCs have been reported to occur in conjunction with associated pathology (secondary ABC), including osteoblastoma, chondroblastoma, giant cell tumors, osteogenic sarcoma, chondromyxoid fibroma, Langerhans cell histiocytosis, or fibrous dysplasia. 3,4,[9][10][11][12][13][14][15] Although primary ABCs are benign tumors of the bone, they can destroy surrounding bone tissue and enlarge rapidly, as in our illustrative case. ABCs of the skull present with varying symptoms depending on their anatomical location; an enlarging palpable mass, focal tenderness, headache, 3 cranial nerve palsy, 16 seizure, 17 otitis media, 18 vision changes, 19 ptosis or exophthalmos, 18 cerebellar signs, 20 bacterial meningitis, 21 or increased intracranial pressure and hydrocephalus [22][23][24] have all been reported in the literature.…”