The terms lamina propria and submucosa can be used interchangeably because these structures tend to merge when there is no muscularis mucosae.
Invasion of the mucosa may be interpreted by the pathologist as either in situ or invasive; determine whether the pathologist is describing in situ or localized tumor.
It is important to have a deep resection in order to adequately assess involvement of the bladder wall muscle.
Superficial muscle invasion is defined as less than half-way through the muscle coat (three layers).
Deep muscle invasion is considered half-way or more through the muscle coat.
If the depth of muscle invasion is not stated by the surgeon or pathologist, stage as T2, invasion of superficial muscle.
There is a high degree of correlation between the grading (differentiation or aggressiveness) of the tumor and the stage (invasiveness).
It is important to differentiate between negative nodes and no information on nodes. There must be some kind of examination beyond a TUR to determine if regional nodes are negative.
Guidelines for Jewett Staging
- It is important to have good surgical or biopsy specimens so that muscle layers can be seen and assessed.
- The prognostic dividing line is between B1 and B2, so read carefully the description of the depth of muscle invasion.
- AJC Tumor notation T1 to T4 parallels Jewett stages A, B, C, and D; N (node) and M (metastases) are part of Jewett stage D.
In the AJCC staging system for Tumor, the suffix "m" may be added to indicate a multifocal tumor; such as T2m.
Cystectomy is usually not considered a treatment option unless the stage is at least Stage II, unless the tumor is superficially extensive.
Papillary and in-situ tumors can have a long protracted course with multiple recurrences and then suddenly become invasive.
Distinguishing Noninvasive and Invasive Bladder Cancer
The two main types of bladder cancer are the flat (sessile) variety and the papillary type. Only the flat (sessile) variety is called in situ when tumor has not penetrated the basement membrane. Papillary tumor that has not penetrated the basement membrane is called non-invasive, and pathologists use many different descriptive terms for noninvasive papillary transitional cell carcinoma. Frequently, the pathology report does not contain a definite statement of noninvasion; however, noninvasion can be inferred from the microscopic description. The more commonly used descriptions for noninvasion are listed below. All are considered summary stage in situ.
Definite Statements of Non-invasion
- Non-infiltrating; non-invasive
- No evidence of invasion
- No extension into lamina propria
- No stromal invasion
- No extension into underlying supporting tissue
- Negative lamina propria and superficial muscle
- Negative muscle and (subepithelial) connective tissue
- No infiltrative behavior/component
Note: These descriptions of non-invasion apply to bladder cases only.
Inferred Description of Non-invasion
- No involvement of muscularis propria and no mention of subepithelium/submucosa
- No statement of invasion (microscopic description present)
- (Underlying) Tissue insufficient to judge depth of invasion
- No invasion of bladder wall; no involvement of muscularis propria
- Benign deeper tissue
- Microscopic description problematic for pathologist (non-invasion versus superficial invasion)
- Frond surfaced by transitional cells
- No mural infiltration
- No evidence of invasion (no sampled stroma)