Definition
Postoperative spindle cell nodule is a similar lesion occurring after a surgical procedure4. Similar lesion has been reported in the vagina, ureter, urethra and prostate10. It is unclear whether this lesion is truely neoplastic. Inflammatory myofibroblastic tumour of the bladder has been shown to have a t(2;5) translocation involving the ALK-1 gene, and so may be a variant of inflammatory myofibroblastic tumour: this entity was first identified in the lung, but is now known to occur at a range of sites.
Synonyms
Inflammatory pseudotumour, inflammatory pseudosarcomatous fibromyxoid tumour, nodular fasciitis, pseudomalignant spindle cell proliferation, pseudosarcomatous myofibroblastic tumour, reactive pseudosarcomatous response.
Clinical features
This is usually a tumour of adults with a male predominance10, rarely of children7. Patients present with haematuria, pelvic pain, obstructive symptoms or recurrent cystitis2,10. There is often a history of smoking, prior surgery or instrumentation10.
Macroscopic appearance
The most common is the is the dome of the bladder10. The tumour may be polypoidal10 or form a submucosal mass2. The tumour commonly appears gelatinous2.
This is a variably cellular spindle cell tumour. Stellate cells are seen. The cells do not show hyperchomasia or frank atypia10. A single nucleolus is commonly present within each nucleus10. Some nuclei may show a red-brown inclusion10. As at other sites, three patterns occur. Most cases show a mix of patterns7. There are mitoses (3 to 38/10 HPF7) but no abnormal mitotic figures. Atypia is lacking. There may be limited necrosis7. There is a mixed inflammatory infiltrate. The tumour shows a myxoid background with myxoid hypocellular areas near the mucosal surface and greater cellularity more deeply10. Arcing blood vessels may be seen10.
Inflammatory myofibroblastic tumour |
postoperative spindle cell nodule |
Sarcomatoid carcinoma |
Stromal tumour of unknown malignant potential of the prostate |
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8/91, 2/65, 3/46, 12/16 (granular cytoplasmic or linear subplasmalemmal)7, 12/26 (focal in 6 cases, diffusely positive in 6 cases)10 |
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0/51, 0/87 |
0/27 |
0/21 |
0/21, 0/57 |
0/21 |
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8/9 (3 diffuse, 5 focal)1, 2/102, 5/154, 13/16 (AE1/3: 13/16, Cam5.2: 9/16)7, 31/33 (AE1/3: focal in 9 cases, diffusely positive in 22 cases)10 |
2/44 |
5/5 (all focal)1, 2/34, 6/8 (AE1/3: 6/8, Cam5.2: 2/8)7 |
0/27 |
0/21 |
1/2 (focal)1, 3/84, 0/57
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0/21
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8/9 (3 diffuse, 5 focal)1, 3/82, 5/84, 16/167, 23/24 (focal in 9 cases, diffusely positive in 14 cases)10 |
2/44 |
4/5 (2 diffuse, 2 focal)1, 2/34, 6/87, 6/87 |
2/27 |
0/21 |
2/2 (1 diffuse, 1 focal)1, 3/74, 5/57 |
0/21
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7/9 (all focal)1, 2/92, 3/114, 12/157, 21/35 (focal in 15 cases, diffusely positive in 6 cases)10 |
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2/5 (1 diffuse, 1 focal)1, 0/34, 3/87 |
2/27 |
2/21 |
0/21, 0/84, 3/57 |
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8/9 (3 diffuse, 5 focal)1 |
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2/2 (focal)1 |
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6/9 (2 diffuse, 4 focal)1 |
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2/2 (1 focal, 1 diffuse)1 |
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5/84 |
2/34 |
1/24 |
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1/54 |
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10/102, 10/104 |
4/44 |
1/14 |
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7/74 |
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2/82, 4/84 |
1/34 |
1/24 |
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1/84 |
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7/104, 14/15 (weak nuclear staining)7 |
3/44 |
5/8 (strong staining)7 |
0/27 |
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9/9 (in addition, there were two negative cases, but these dated from 1928 and 1929, which might account for loss of immunogenicity.)4, 3/5 (strong staining)7 |
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0/44, 2/157 |
0/34 |
0/87 |
0/27 |
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0/24, 0/57 |
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0/157 |
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0/87 |
0/27 |
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1/57 |
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1/16 (focal weak staining in one case)7 |
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1/87 |
0/27 |
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1/57 |
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The features are those of myofibroblastic cells. Fibronexus junctions are specific to myofibroblastic cells but are not often to be found.
Molecular cytogenetics
Cytogenetic abnormalities at 2p23, the site of the ALK-1 gene, have been reported8. ALK gene translocations examined by FISH are seen in 4 of 6 cases in each of two studies1,10.
Inflammatory myofibroblastic tumour of childhood: is associated with constitutional symptoms. This lesion is more cellular with a dense infiltrated of lymphocytes and plasma cells. There are ganglion-like cells and the lesions show calcification. There is rarely positivity for cytokeratins. This is a tumour of low malignant potential10.
Postoperative spindle cell nodule
Sarcomatoid urothelial carcinoma: may be myxoid. There is marked cytological atypia, abnormal mitoses, non-myxoid areas of greater cellularity. There is often a malignant epithelial component. p53 staining tends to be strong. Staining for cytokeratins may be weak. ALK-1 is negative.
Leiomyosarcoma: may be myxoid and may show positivity for cytokeratins. A delicate vascular network and an inflammatory infiltrate are lacking. ALK-1 is negative. p53 staining may be strong. Any cytokeratin positivity is focal and weak.
Rhabdomyosarcoma: positive for myogenin and Myo-D1. May be positive for ALK-19.
Treatment has variously been by transurethral resection, or partial or total cystectomy10.
The prognosis is good; local resection is adequate. Recurrences may occur10, possibly more often in ALK-1 positive cases7. The tumour does not metastasis10. Unresected lesions may massively enlarge to cause death by obstruction, not metastasis4.
This page last revised 13.7.2006.
©SMUHT/PW Bishop