Our results illustrate that processes other than metastatic prostate carcinoma may cause abnormalities in pelvic lymph nodes sampled at radical prostatectomy. Using the same prostatectomy database, Young et al
found the incidence of metastatic prostate carcinoma at staging lymphadenectomy to be 4.6%.3
In our present study, 1.8% of lymphadenectomy specimens contained incidental lymph node pathology other than metastatic prostate carcinoma.
Histiocytic changes in lymph nodes that drain joint prostheses are well recognised in the orthopaedic literature.4
Case reports have highlighted the potential for these changes to mimic lymphadenopathy as a result of metastatic carcinoma from primary sites, including endometrium, skin, and prostate.4–7
Differential diagnoses of nodal infiltrates containing histiocytic cells include infections (mycobacterium—for example, Mycobacterium leprae
and Whipple's disease8
), Rosai-Dorfman disease, lymphangiographic changes, Langerhan's cell histiocytosis, monocytoid B cell hyperplasia, virus associated haemophagocytic syndrome, metastatic melanoma,8
However, the presence of CD68 positive macrophages containing birefringent particles within their cytoplasm confirms the diagnosis of sinus histiocytosis related to previous joint prosthesis surgery.4
“As the prognosis in cases of Hodgkins lymphoma is often good, the associated lymphadenopathy should not necessarily prevent radical prostatectomy for gland confirmed adenocarcinoma ”
Granulomatous inflammation of lymph nodes is also well recognised and may relate to several different disease processes. Infective agents are one well documented cause of this change. Other causes include secondary responses in nodes draining carcinoma or in association with Hodgkin's disease, other lymphomas, and foreign body reactions. Foreign body granulomas have been described in lymph nodes draining silicone implants of the metatarsal joints and from silicone genitourinary prostheses.10,11
In the cases described special stains and subsequent clinical investigation did not clarify the aetiology.
Take home messages
- Processes other than metastatic prostate carcinoma may cause abnormalities in pelvic lymph nodes sampled at radical prostatectomy
- Incidental pathology was present in 15 of 854 (1.8%) patients who underwent pelvic lymphadenectomy during radical prostatectomy and only one of these 15 patients had concomitant metastatic prostate carcinoma
- Awareness of possible non-metastatic lymph node pathology aids histological diagnosis and may be clinically relevant
An incidental finding of non-Hodgkin's lymphoma is not uncommon, especially in an older male population, and has been reported previously in association with localised prostate carcinoma.12
A history of haematological malignancy should be considered as a cause of pelvic lymphadenopathy, especially if nodal enlargement is bilateral. Because the prognosis in such cases is often good, the associated lymphadenopathy should not necessarily prevent radical prostatectomy for gland confined adenocarcinoma.13,14
The remaining cause of unilateral incidental “pelvic lymphadenopathy” was a foreign body giant cell reaction to a synthetic mesh, which had migrated from a previous hernia repair. In this case, radical surgery was initially abandoned as metastatic prostatic carcinoma was assumed to be the cause. Surgery was completed by the perineal route, once the true nature of the histological changes associated with the lymph nodes had been identified.
Clearly, any of these incidental findings may occur in addition to metastatic prostate carcinoma. Only one of the 15 cases described here included concomitant metastatic prostate carcinoma. In our series, with one exception, the incidental pathology has not caused changes in surgical management, although the potential for misdiagnosis is noted in the literature.4–7
The postoperative diagnosis of the haematological malignancies has clinical implications.