Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Granular cell tumour
I.A. Sesterhenn
Definition
A circumscribed tumour consisting of
nests of large cells with granular
eosinophilic cytoplasm due to abundant
cytoplasmic lysosomes.
ICD-O code 9580/0
Epidemiology
This tumour is rarely seen in the urinary
bladder. The 11 cases reported in the
literature and the 2 cases in the
Bladder Tumour Registry of the Armed
Forces Institute of Pathology occurred
in adult patients from 23-70 years
of age {88,779,1631,1752,1821,1949,
2351,2881}. There is no gender predilection.
Macroscopy
The tumours are usually solitary, well circumscribed
and vary in size up to 12 cm.
Histopathology
Microscopically, the cells have abundant
granular eosinophilic cytoplasm and
vesicular nuclei. S-100 protein can be
identified in the tumour cells {2490}. A
congenital granular cell tumour of the
gingiva with systemic involvement
including urinary bladder has been
reported {2011}.
Prognosis
To date, only one malignant granular cell
tumour of the bladder has been
described {2153}.
Fig. 2.82 Granular cell tumour of the urinary bladder.
Neurofibroma
L. Cheng
Definition
A benign mesenchymal tumour occurring
in a urinary bladder wall consisting
of a mixture of cell types including
Schwann cell, perineurial like cells and
fibroblasts.
ICD-O code 9540/0
Epidemiology
Neurofibromas of the urinary bladder
occur infrequently; fewer than 60 cases
have been reported. The tumours typically
occur in young patients with neurofibromatosis
type 1. The mean age at
diagnosis is 17 years, and the male-tofemale
ratio is 2.3:1 {434}.
Clinical features
Patients typically exhibit physical stigmata
of neurofibromatosis type 1. The urinary
bladder is the most common site of
genitourinary involvement in neurofibromatosis,
and involvement of the bladder
is often extensive, necessitating cystectomy
in approximately one-third of cases.
Clinical signs include hematuria, irritative
voiding symptoms, and pelvic mass.
Macroscopy
The tumours frequently are transmural,
showing a diffuse or plexiform pattern of
growth.
Histopathology
Histologically, the tumours are usually of
the plexiform and diffuse type.
Neurofibroma of the bladder is characterized
by a proliferation of spindle cells
with ovoid or elongate nuclei in an Alcian
blue positive, variably collagenized
matrix. Cytoplasmic processings of
tumour cells are highlighted on
immunostaining for S-100 protein.
Differential diagnostic considerations
include low grade malignant peripheral
nerve sheath tumour, leiomyoma, postoperative
spindle nodule, inflammatory
pseudotumour, leiomyosarcoma, and
rhabdomyosarcoma. It is critical to distinguish
neurofibrooma of atypical or cellular
type from malignant peripheral nerve
sheath tumour. Atypical neurofibromas
lack mitotic figures or appreciable MIB-1
labeling. Cellular neurofibromas lack significant
cytologic atypia or mitotic figures.
The finding of rare mitotic figures in
a cellular neurofibroma is not sufficient
for a diagnosis of malignancy {434}.
Adequate sampling is critical when
increased cellularity is noted in superficial
biopsies.
Prognosis
Long-term urinary complications include
bladder atony, neurogenic bladder, and
recurrent urinary tract infection with
hematuria. Only 4 tumours (7%) underwent
malignant transformation, none of
these occurred in children {434,1737}.
Leiomyoma / Other non-epithelial tumours / Granular cell tumour / Neurofibroma 145