Pathomorphologie des parossalen Osteosarkoms Erfahrungen an 125 Fällen des Hamburger Knochentumor-Registers

Abstract

Parosteal osteosarcoma is a rare low-grade bone tumor. It occurs between the 2nd and 8th decade of life. In our own series of 125 parosteal osteosarcomas, most patients were aged between 30 and 40. The most frequent location was the distal dorsal femur. Until clearly proven otherwise, a bone-forming tumor in this location has to be regarded as a parosteal osteosarcoma. Of all parosteal osteosarcomas 77% are located in the lower extremity, with a female sex predominance in this location (62%); 18% are located in the upper extremity; 15% of all parosteal osteosarcomas are located in the humerus. Just 6% of all parosteal osteosarcomas are observed in the skull, the spine, and the pelvis. The tumor is characterized by hyalinized fibrous stroma with a low cell content without substantial nucleus polymorphism and variably dense bony trabeculae. The diagnosis can be difficult due to highly differentiated areas with fat tissue within the marrow and very uniformly bony structure. The operation material has to be analyzed very carefully, because the extent of dedifferentiated areas and most probably also the extent of invasion of the medullary cavity determine the prognosis and occurrence of recurrencies. The tumor is most commonly misinterpreted as osteochondroma or heterotopic ossification. Paying attention to all radiologic and histologic criteria,osteoblastic eccentrically located high-grade osteosarcomas can be clearly distinguished from parosteal osteosarcoma. An intramedullary located low-grade osteosarcoma,which is differentiated like a parosteal osteosarcoma,is histologically indistinguishable from the parosteal variant. This variant requires the synthesis of all available data to find the correct diagnosis. The parosteal osteosarcoma shows like no other tumor the necessity of close cooperation of all involved disciplines for diagnosis and therapy.

Diagnostic and treatment problems with parosteal osteosarcoma. A clinical and a histological study of 7 cases and review of the literature

“…The differential diagnosis may include diverse entities such as: myositis ossificans, fracture callus, ossifying haematoma, osteochondroma, extraosseus osteosarcoma, parosteal chondroma, desmoplastic fibroma and osteoma. 3,4,5,7,13 The clinical characteristic of patients who have a parosteal osteosarcoma is distinctly different from that of patients who have conventional osteosarcoma. 2,13 The most common complain was "painless swelling", the same as reviewed in the literature, presented with 3 patients.…”

“…The operation material must undergo a careful patohistological analysis, because the extent of invasion of the medullar cavity and most probably the extent of dedifferentiated areas determines the prognosis and occurrence of local recurrence and metastases. 4,5 As most authors report, a wide margin of excision ensures the adequate surgical treatment of parosteal osteosarcoma in any surgical grade or stage. No evidence for the development of primary tumour satellite nodules or of "skip" metastases were seen, so it would seem that truly radical or compartmental surgery is rarely indicated.…”

Parosteal osteosarcoma with focal fatty metaplasia: A case report

“…PO mainly affects adults between the ages of 20-30 years and exhibits a slightly higher prevalence in women. The most common sites affected by PO include the knee, accounting for about 70% of cases [2] , and specifically the posterior aspect of the distal femur, followed by the proximal tibia, proximal humerus, fibula, radius, and ulna; only 6% of all POs are observed in the skull, the spine, and pelvis [3] .…”

“…Grossly, the tumor appears as a hard lobulated mass attached to the underlying external layer of periosteum, and may contain nodules of cartilage within the substance of the tumor or an incomplete cartilage cap at the surface [4] . Microscopically, PO is characterized by hyalinized fibrous stroma with a low cell content without substantial nucleus polymorphism and variably dense bony trabeculae [3] . In some cases, the diagnosis of PO can be complicated by the presence of highly differentiated areas with fatty tissue within the marrow and uniform bony structure [3] .…”

“…Microscopically, PO is characterized by hyalinized fibrous stroma with a low cell content without substantial nucleus polymorphism and variably dense bony trabeculae [3] . In some cases, the diagnosis of PO can be complicated by the presence of highly differentiated areas with fatty tissue within the marrow and uniform bony structure [3] .…”