Benign Nerve Sheath Tumors on Urinary Bladder Biopsy

Abstract

Benign nerve sheath tumors (schwannoma and neurofibroma) involving the urinary bladders are rare with only case reports and limited series. We identified 6 neurofibromas and 2 schwannomas involving the urinary bladder. Of the 8 cases, 7 were sent to one of the authors in consultation and the last came for treatment to The Johns Hopkins Hospital. Patients (3 males, 5 females) ranged in age from 3 to 69 years old (average 36 y old). Presenting symptoms included recurrent infection in 6 patients, hematuria in 3 patients, and irritative symptoms in 3 patients (some patients with 2 symptoms). Three patients had a pelvic mass on physical examination. Three patients (3/8) had a solitary lesion in the bladder, 4 patients (4/8) had multifocal lesions, and 1 patient had no information available. Five patients underwent local resection. One patient, who was 3 years old, had multiple plexiform neurofibromas within the bladder and did not have surgical treatment and another patient is also undergoing surveillance. One patient had no treatment information available. Seven patients had clinical follow-up information available. The length of follow-up varied from 2 to 124 months (average 47 mo). Three out of the seven patients with follow-up information had neurofibromas in other sites, including the skin, uterus, mesentery, and ureter. One patient was known to have other stigmata of neurofibromatosis. Both cases with schwannoma had only bladder involvement. No family history of neurofibromatosis and no genetic studies were performed on any of the patients. Three neurofibromas were of the diffuse type, with 2 cases plexiform, and 1 case could not be subtyped. Neither recurrence nor malignant transformation was demonstrated on follow-up. The importance of accurately diagnosing plexiform neurofibromas of the bladder is that a subset harbors neurofibromatosis. If the lesion is focal, conservative excision is the choice of treatment with a low risk of recurrence. Diffuse neurofibromas can be difficult to diagnose leading to delay of treatment and potentially the need for a more extensive excision. Once recognized as a neurofibroma, it is important to identify it as a diffuse neurofibroma, given its lack of relationship to neurofibromatosis.

Primäres diffuses Neurofibrom der Harnblase

“…Das primär diffuse Neurofibrom der Harnblase ist unter den Fibromen der Harnblase eine Rarität. In der Literatur finden sich lediglich 6 histologisch gut dokumentierte Fälle von rein diffusen Neurofibromen der Harnblase [2,5,6,7].…”

“…Die meisten Patienten wurden mittels lokaler und transurethraler Exzision oder Zystektomie behandelt und haben ohne Anhalt für Rezidive überlebt [6]. Die Möglichkeit einer malignen Entartung beim primär diffusen Neurofibrom wurde bisher nicht beschrieben.…”

Spindle cell lesions of the bladder and urinary tract

“…Occasionally, malignant peripheral nerve sheath tumour has arisen 94 either in a longstanding neurofibroma or ganglioneuroma 95 . Rare cases of schwannoma of bladder have been recorded 87,96 …”

“…There are multiple case reports and several small series of neurofibroma involving the urinary bladder. [85][86][87] They may be very large, distorting the entire bladder resulting in atony or neurogenic bladder. 86,88 The histological features (Figures 15 and 16) are those of neurofibroma arising elsewhere, and approximately half of cases have other sites of involvement.…”

“…95 Rare cases of schwannoma of bladder have been recorded. 87,96 Solitary fibrous tumour Solitary fibrous tumour ( Figure 17) has been described in the urinary bladder in rare instances. [97][98][99][100][101] Those reported thus far have followed a benign clinical course.…”