The Prognostic Value of a Primary Inverted Papilloma of the Urinary Tract

Abstract

Purpose: Ever since the recognition of the inverted papilloma as a distinct lesion of the urinary tract, there has been discussion about the possible (pre)malignant potential of this rare tumor, with subsequent uncertainty about followup. Hampering the discussion are the low frequency, the unknown etiology, the difficult histopathological diagnosis and the reported association with transitional cell carcinoma. We reviewed the literature and studied our patients, resulting in the largest series reported in the literature to date. Materials and Methods: We selected 51 patients with an inverted papilloma without a history of or a concordant transitional cell carcinoma of the urinary tract. Histology of all patients was reviewed.Results: After review, as many as 14 patients appeared to be misdiagnosed (transitional cell carcinoma in 11)* In 37 patients, we could confirm the diagnosis of inverted papilloma, with characteristics that were highly comparable to those described in the literature. Only 1 patient had a superficial bladder tumor after 49 months.Conclusions: Reviewing these data and our own results, we conclude that an inverted papil loma does not seem to be a risk factor for transitional cell carcinoma, although inverted papillomas and transitional cell carcinoma appear to be related to some extent. Therefore, frequent and long-term followup does not seem to be necessary provided that there is no doubt about the difficult histological diagnosis.

Inverted urothelial papillomas with foamy or vacuolated cytoplasm

“…Although the lesion in case 1 recurred, the second lesion displayed typical inverted papilloma morphology. Although short (1 year), the lack of urothelial disease on cystoscopic follow-up after the recurrence is consistent with the concept that recurrence may not be equivalent to progression for inverted papillomas [9]. Furthermore, it is at least possible to suggest that the b recurrence Q in case 1 represented incomplete resection of the original lesion, necessitating reexcision rather than true re-growth.…”

“…All of our cases had areas that were classic for inverted papilloma. If one applies these criteria strictly, then inverted papillomas are lesions that may recur, but behave in a uniformly benign fashion without metastatic potential [9].…”

“…They predominantly occur in males [6 -9], present clinically with hematuria or dysuria, and have a smooth polypoid appearance on gross or cystoscopic examination [8]. Although the classic morphologic criteria for inverted papilloma have long been defined [10], reported cases with aberrant cytologic features have caused significant confusion regarding the biologic potential of inverted papilloma [3,4,9,11]. The current study 0046 describes a series of inverted papilloma with foamy (xanthomatous-appearing) or vacuolated cytoplasm, findings that may cause sufficient cytologic and architectural distortion to suggest a diagnosis of urothelial carcinoma.…”

Unique clinicopathologic and molecular characteristics of urinary bladder tumors in children and young adults

“…Initially termed "adenomatoid polyp" [50] and later described under its current name [51], inverted papilloma is usually found in males in the sixth or seventh decade of life, with an even more striking male predilection (7:1) than typical urothelial papilloma [52][53][54][55][56]. Its occurrence in pediatric patients is unusual; however, occasional cases have been identified [57,58].…”

Atypia in inverted urothelial papillomas: Pathology and prognostic significance

“…Again, this biological behavior most closely resembles that of inverted papillomas without atypia, which rarely recur with complete resection and have not been shown to metastasize. 5 This is in contrast to transitional cell carcinomas, which have reported recurrence rates of 45 to 60%. 3,21 In summary, we have reported 11 cases of inverted papillomas with atypical features.…”