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

Somatic genetics
Ultrastructure, antigenic composition, and
DNA- content of inverted papilloma cells
have been non-contributory to the diagnosis
in the few evaluated cases
{68,447,1190,1406}.
Prognosis
If the diagnosis of inverted papilloma is
strictly confined to the criteria described
above, these tumours are benign.
Recurrent lesions have been observed in
less than 1% of the reported cases {376}
and progression from pure inverted papilloma
to carcinoma is extremely rare. An
initial diagnosis of inverted papilloma
should be challenged if progression is
observed as many recurring or progressing
cases have exophytic papillary structures
in their initial biopsy {78}.
Papillary urothelial neoplasm of low
malignant potential
S.L. Johansson
C. Busch
Definition
Papillary Urothelial Neoplasm of Low
Malignant Potential (PUNLMP) is a papillary
urothelial tumour which resembles
the exophytic urothelial papilloma, but
shows increased cellular proliferation
exceeding the thickness of normal
urothelium.
ICD-O code 8130/1
Epidemiology
The incidence is three cases per 100,000
individuals per year. The male to female
ratio is 5:1 and the mean age at diagnosis
(+/- standard deviation) is 64.6 years
+/-13.9 years (range 29-94) {1107}. The
latter is virtually identical to that of 112
patients treated at the Mayo Clinic {432}.
Localization
The lateral and posterior walls close to
Fig. 2.35 Macroscopic appearance of a non-invasive
low grade urothelial carcinoma with delicate
papillae obtained at time of transurethral resection.
the ureteric orifices are the preferred
sites for these tumours.
Clinical features
Most patients present with gross or
microscopic hematuria. Urine cytology
is negative in most cases. Cystoscopy
reveals, in general, a 1-2 cm regular
tumour with a appearance reminiscent
of "seaweed in the ocean". Complete
transurethral resection is the treatment
of choice.
Histopathology
The papillae of PUNLMP are discrete,
slender and non fused and are lined by
multilayered urothelium with minimal to
absent cytologic atypia. The cell density
appears to be increased compare to normal.
The polarity is preserved and there
is an impression of predominant order
with absent to minimal variation in architectural
and nuclear features. The nuclei
are slightly enlarged compare to normal.
The basal layers show palisading and
the umbrella celI layer is often preserved.
Mitoses are rare and have a basal location.
These architectural and cytological
features should be evaluated in well oriented,
non tangentional cut areas of the
neoplasm. The tumours are predominantly
diploid.
Prognosis
The prognosis for patients with PUNLMP
is excellent. Recurrences occur, but at a
significantly lower frequency than in noninvasive
papillary carcinomas {1610}.
Rarely, these patients may present with
another tumour of higher grade and/or
stage, usually years after the initial diagnosis.
In a series of 95 cases, 35% had
recurrence but no tumour progressed. If
the patients were tumour free at the first
follow-up cystoscopy, 68% remained
tumour free during a follow-up period of
at least 5 years {1104,1110}. In another
study, 47% of the patients developed
local recurrence but none of the 19
PUNLMP patients progressed {2071}. In
contrast, in a retrospective study of 112
patients with long term follow up, four
patients progressed in stage, two to
Fig. 2.36 Non-invasive urothelial neoplasm. Papillary
urothelial neoplasm of low malignant potential.
Inverted papilloma / Papillary urothelial neoplasm of low malginant potential 115