Search

Hyalinising spindle cell tumour with giant rosettes (HSCTGR) is an uncommon, recently described low-grade sarcoma which shares many histological features with low-grade fibromyxoid sarcoma (LGFMS). We report a case of HSCTGR occurring in the deep soft tissues of the thigh of a 46-year-old woman, that presented as a slowly growing, painless mass. Microscopically the tumour was composed of spindled stromal cells amongst which were scattered so-called collagen rosettes. The distinctive feature of this case was the previously unreported finding of lymphoid cells of T-cell phenotype admixed with fibrohistioctyic cells in the cellular cuff surrounding the collagenous core of the rosettes. The case was further unusual in that it included focal areas of increased cellularity with a mitotic count of up to three per 10 high-power fields. While the latter feature has been associated with increased recurrences and metastases in LGFMS, it is not known whether the significance is similar in HSCTGR. The spindled stromal cells showed ultrastructural features of poorly differentiated fibroblasts, while those at the edges of the rosettes showed features of altered fibroblasts, some with a fibrohistiocytic appearance. These findings support the interpretation that HSCTGR forms part of the spectrum of sarcomas showing fibroblastic differentiation.

A 33 yr old man with a history of pilomatrixoma of the scalp, presented 5 mths later with a metastatic undifferentiated carcinoma in a submandibular lymph node. The cutaneous and lymph node tumors showed close histological similarity and features of malignancy. Investigations over 30 mths excluded a primary neoplasm elsewhere and consequently led to the diagnosis of malignant pilomatrixoma. These tumors are rare and most often located on the scalp. Most of the affected patients are middle age males. Wide excision is advised to avoid recurrences.

Osteofibrous dysplasia (ossifying fibroma of long bone) is an uncommon disorder of bone affecting the tibia and, rarely, the fibula of children and adolescents. It has been delineated from monostotic fibrous dysplasia, from which it can be distinguished by its radiological and histological characteristics and by its clinical course. We report 11 patients with osteofibrous dysplasia whose ages ranged from 10 months to 22 years. Four presented with a pathological fracture and in 2 a pseudarthrosis developed. A circumscribed area of intracortical lucency and expansion in the diaphysis is the characteristic radiological finding. Histologically there is a similarity to fibrous dysplasia but the trabeculae are lamellar or have a lamellar surface and most show osteoblastic rimming. Treatment may be difficult but more recent experience strongly favours a conservative approach wherever possible.

Five cases of infection due to an unusual mycobacterium are recorded, and the growth requirements and histological findings are discussed. On initial culture, these mycobacteria could be grown only on Lowenstein-Jensen medium containing ferric ammonium citrate, and the histology of the skin lesions was not always typical of mycobacterial disease.