Histological patterns of bone and articular tissues after orthopaedic reconstructive surgery (artificial joint implants)

Foreign body histiocytosis reaction after hip replacement with concomitant metastatic adenocarcinoma in the same lymph node

Infiltration of regional lymph nodes by macrophages has been shown after total joint arthroplasty. These pelvic lymph nodes were obtained most often from patients during staging procedures for carcinoma and may be a diagnostic pitfall in the frozen section diagnosis of nodal metastasis. We report an unusual case of association in the same lymph node between histiocytosis and prostatic carcinoma metastasis. Histiocytosis was caused by wear debris from two different prostheses. Inductively coupled plasma mass spectrometry verified this diagnosis.

Osteoclasts are capable of particle phagocytosis and bone resorption

Osteoclasts are multinucleated cells specialized for the function of lacunar bone resorption. Although they are known to be capable of phagocytosis of inert particles, it is not known whether this abolishes their ability to respond to hormones or to form resorption lacunae. Human and rat osteoclasts were isolated from giant cell tumours of bone and rat long bones, respectively, and cultured on coverslips and cortical bone slices, both in the presence and in the absence of particles of latex (1 micron diameter) and polymethylmethacrylate (PMMA) (< 50 microns). By light microscopy, it was evident that osteoclasts which had phagocytosed both latex and PMMA particles remained responsive to calcitonin. Osteoclast phagocytosis of particles was also evident on scanning electron microscopy, where it could also be seen that these cells were associated with the formation of resorption lacunae. These findings underline the fact that the osteoclast is a true member of the mononuclear phagocyte system and that phagocytosis does not abrogate either its hormonal response to calcitonin or its highly specialized function of bone resorption. That osteoclasts which have phagocytosed biomaterial particles such as PMMA are still able to carry out lacunar bone resorption is of interest in clinical conditions such as aseptic loosening, where a heavy foreign body particle load is often associated with extensive bone resorption.

Postarthroplasty histiocytic lymphadenopathy in gynecologic oncology patients. A benign reactive process that clinically may be mistaken for cancer

BACKGROUND

A distinctive histiocytosis occurs in the regional draining lymph nodes after large joint replacements, resulting in lymphadenopathy that may mimic cancer both grossly and microscopically. Postarthroplasty histiocytic lymphadenopathy has most often been observed in males during surgery for prostate cancer.

METHODS

The authors present three examples of postarthroplasty histiocytic lymphadenopathy that occurred in gynecologic oncology patients. We studied the clinical, histologic, and immunohistochemical features of all three cases and the ultrastructure of one of them.

RESULTS

Most involved lymph nodes were enlarged, but histiocytosis was also seen in normal sized lymph nodes. Microscopically, histiocytes with abundant granular cytoplasm were present in the lymph node parenchyma, and, to a lesser extent, in the sinuses. Normal lymph node architecture was variably effaced and the histiocytic infiltrate extended focally into the perinodal tissue. Small, black metal particles were present in the histiocytes in every case. Birefringent polyethylene particles were a prominent finding in all three cases as confirmed by positive modified oil red O staining, and, in one case, by electron microscopy. The histiocytes were strongly immunoreactive for CD68, but immunostains for S100 protein, MAC 387, and cytokeratin were negative.

CONCLUSIONS

Enlargement of the lymph nodes in cancer patients who have had large joint replacements may be due to a benign histiocytosis rather than to metastatic cancer. The histologic features of the lymphadenopathy are distinctive and recognizable in routine histologic preparations. Polyethylene wear particles shed from joint prostheses are the most common substances in the histiocytes and are the most likely cause of the histiocytosis.