It is believed that testicular/paratesticular fibrous pseudotumours are reactive lesions that can involve paratesticular tissues, testicular tunics, epididymis and/or the spermatic cord.1–5
A recent study showed that, based on 13 cases, fibrous pseudotumour can be histologically subdivided into 3 categories: (1) plaque-like (dense fibrosis without significant inflammation); (2) inflammatory sclerotic (dense fibrosis with significant inflammation); and (3) myofibroblastic (reactive looking, tissue-culture like cells with numerous capillaries and sparse inflammation).5
Immunohistochemical analysis in their study showed overlapping features of the profile with variable morphologic patterns, suggesting that testicular/paratesticular fibrous pseudotumour could be the result of several distinct processes. Because stains for ana-plastic lymphoma kinase-1 and β-catenin were negative in all the above subtypes, there seemed to be no correlation between testicular/paratesticular fibrous pseudotumour and inflammatory myofibroblastic tumour or fibromatosis seen in other organs.5
Historically, fibrous pseudotumours have been referred to by multiple names including fibromatous periorchitis, nonspecific paratesticular fibrosis, nodular fibropseudotumour, reactive periorchitis, fibroma, fibrous pseudotumour, pseudofibromatous periorchitis, proliferative funiculitis and several others.2,5,6
However, because some lesions lack inflammatory component and are not nodular, the less specific term “fibrous pseudotumour” was preferred.5
Although fibrous pseudotumours are non-neoplastic lesions, many patients will undergo radical orchiectomy for suspicion of malignancy. Considering this process is often localized and occurs in younger males, testicular sparing surgery should be considered a possibility. The diffuse form of fibrous pseudotumour can be extremely difficult to excise and testicular-sparing surgery has rarely been reported in the literature for this lesion. In the current study, we detail 5 cases of testicular/paratesticular fibrous pseudotumour where the use of FSA led to the diagnosis of this reactive, non-neoplastic lesion. Nonetheless, the first, second and third cases underwent orchiectomy. Major reasons for radical surgery included questionable viability of the testicle due to inflammatory and/or infiltrative conditions and inability to definitively rule out a lymphoproliferative malignancy. In the fourth and fifth cases, intraoperative suspicion was for a benign lesion. Diagnosis via frozen section was useful for intraoperative management and conversion from radical orchiectomy to testicular-sparing surgery.
Histologically, the differential diagnosis for testicular/paratesticular fibrous pseudotumour may include fibrous mesothelioma, neurofibroma, leiomyoma, idiopathic fibromatosis, unclassified sex cord-stromal tumour, angiomyo-fibroblastoma, solitary fibrous tumour, leiomyosarcoma, fibrosarcoma and malignant fibrous histiocytoma.1,2,6
It is usually possible to distinguish between these entities via the morphological appearance of the lesion, in conjunction with immunohistochemical stains and the presence or absence of infiltration into the surrounding tissue. However, at the time of intraoperative FSA, it may be difficult to make a definitive diagnosis of fibrous pseudotumour on a limited specimen. Indeed, in 4 of the 5 cases (cases 1, 2, 3, and 5), diagnoses made by general surgical pathologists were rather descriptive. Furthermore, despite the frozen section diagnosis describing a definitive process in two cases (cases 1 and 2), orchiectomy was ultimately chosen. Urologists should be aware of this entity as reactive in nature and its variable gross findings including firm mass(es) and diffuse fibrous proliferation encasing the testicle. In select cases, intraoperative FSA for testicular/paratesticular fibrous pseudotumour may play a significant role in obviating radical orchiectomy.