Cervix
Mesenchymal / mixed epithelial & mesenchymal tumors
Postoperative spindle cell nodule
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PubMed Search: Postoperative spindle cell nodule
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Pathophysiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Farran S, Chapel DB. Postoperative spindle cell nodule. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixpostoperativespindlecell.html. Accessed April 1st, 2025.
Definition / general
- Benign spindle cell proliferation that presents as a rapidly growing submucosal mass ~2 - 10 weeks after surgery or instrumentation
Essential features
- Develops ~2 - 10 weeks after mucosal surgery or instrumentation
- Poorly circumscribed proliferation of plump, reactive appearing myofibroblastic cells often with brisk mitoses and frequent surface ulceration
- Local excision is adequate management and positive margins are not prognostically adverse
Terminology
- Postoperative spindle cell nodule was coined in 1984 by Proppe, Scully and Rosai and remains the recommended WHO terminology (Am J Surg Pathol 1984;8:101)
- Inflammatory pseudotumor and postoperative pseudosarcoma are discouraged
Epidemiology
- Vulvovaginal cases reported in women aged 20 - 61 years (Am J Surg Pathol 1984;8:101, Histopathology 1995;26:571, Am J Dermatopathol 1999;21:220)
- Endometrial and cervical cases reported in women up to age 75 years (Arch Pathol Lab Med 1988;112:566, Int J Gynecol Pathol 1985;4:255)
Sites
- Vulva and vagina are most commonly involved sites in female genital tract, with rare cases reported in endometrium and cervix
- Analogous lesions reported in the oral cavity, skin, urinary bladder, prostatic urethra and breast (Am J Surg Pathol 1984;8:101, Histopathology 1995;26:571, Am J Dermatopathol 1999;21:220, Pathol Int 2008;58:787)
- Rare cases in the breast, endometrium and cervix (Arch Pathol Lab Med 1988;112:566, Int J Gynecol Pathol 1985;4:255)
- Nodule is most often centered on / based in the surgical incision site
Pathophysiology
- Initially proposed to represent a postsurgical reparative process, though recent data suggest it may be a transient USP6 rearranged neoplasm, molecularly analogous to nodular fasciitis (Arch Pathol Lab Med 1988;112:566, Histopathology 2023;82:587)
- Trisomy 7 has been reported in 2 cases (vulva and bladder), though the significance of this finding is unclear (Cancer Genet Cytogenet 2007;174:147)
- Pseudosarcomatous myofibroblastic proliferations of the urinary bladder have been regarded by some as equivalent to postoperative spindle cell nodules in the bladder
- Recent data suggest that ALK rearrangements are present in ~85% of pseudosarcomatous myofibroblastic proliferations of the urinary bladder (Mod Pathol 2021;34:469)
- ALK rearrangements are not described in postoperative spindle cell nodules of the female genital tract
Clinical features
- Rapidly growing, tender polypoid mass, typically involving the surgical incision site, presenting 2 - 10 weeks after surgery / instrumentation (Histopathology 1995;26:571)
Diagnosis
- Triad of characteristic histopathologic features, characteristic clinical context and exclusion of more clinically significant mimics
- Confirmation of USP6 rearrangement may be diagnostically useful, though data are limited (Histopathology 2023;82:587)
Prognostic factors
- Excellent prognosis
- Conservative local excision is adequate management
- Positive margins are common but are not prognostically adverse
- Local recurrence has been reported, typically within a few weeks of initial excision; in which case, repeat local excision is adequate
- All reported patients were disease free with long term (months to years) follow up (Am J Surg Pathol 1984;8:101, Histopathology 1995;26:571, Am J Dermatopathol 1999;21:220)
Case reports
- 33 year old woman with painful swelling at the site of a Bartholin cyst excision operation (Histopathology 1995;26:571)
- 39 year old woman underwent a cervical cone biopsy for cervical intraepithelial neoplasia 3 (CIN3) and a partial vulvectomy for vulval intraepithelial neoplasia 3 (VIN3) 4 years later, with a nodule within the vulvar scar (Cancer Genet Cytogenet 2007;174:147)
- 74 year old woman with a new endocervical nodule 2 weeks following endometrial curettage for endometrial adenocarcinoma (Int J Gynecol Pathol 1985;4:255)
Treatment
- Conservative local excision is adequate management
- Positive margins do not portend an adverse outcome, so re-excision for positive margins is likely unnecessary, particularly in the absence of clinical regrowth
- In the event of local recurrence, repeat conservative local excision is adequate
- References: Histopathology 1995;26:571, Am J Surg Pathol 1984;8:101
Gross description
- Irregular, ill defined, soft polypoid nodule (Am J Surg Pathol 1984;8:101, Histopathology 1995;26:571)
- Surface erosion is often present
- Typically 2 - 4 cm, though there have been reported cases up to 5 cm (Histopathology 1995;26:571)
- Soft, reddish gray to tan-yellow cut surfaces
- Gross hemorrhage may be seen
Microscopic (histologic) description
- Poorly circumscribed spindle cell lesion, frequently infiltrating surrounding tissues
- Intersecting fascicles of plump to elongated, tapered spindle cells with moderate to abundant eosinophilic cytoplasm, ovoid nuclei, evenly dispersed chromatin and prominent nucleoli (Am J Surg Pathol 1984;8:101, Histopathology 1995;26:571)
- Mitoses brisk (up to 20 per 10 high power fields [HPF])
- Atypical mitoses are absent
- Surface ulceration is common but coagulative necrosis is absent
- Spindle cells separated by delicate fibrous stroma with small, thin walled vessels
- Chronic inflammatory infiltrate is common; acute inflammation may accompany surface erosion
- Stromal hemorrhage is frequently present
Microscopic (histologic) images
Contributed by Aarti Sharma, M.D.
Whorled architecture
Myxoid stroma
Chronic inflammation
Mitotic activity
Bland cytomorphology
Positive stains
- Smooth muscle actin is consistently positive but may be focal (Histopathology 2023;82:587)
- Desmin is positive in a subset; typically focal (Histopathology 2023;82:587, Histopathology 1995;26:571)
Negative stains
- Cytokeratins (rarely focal weak staining) (Histopathology 2023;82:587)
- S100
- ALK
- Vascular markers (CD31, CD34, ERG)
- HHV8
Molecular / cytogenetics description
- Recurrent USP6 rearrangements were recently described (Histopathology 2023;82:587)
- RNA sequencing in 1 case revealed an MYH9::USP6 fusion
- Fluorescence in situ hybridization or next generation sequencing based techniques may be used to detect USP6 alterations, though the practical application of molecular testing as a diagnostic tool in this context remains unverified
Sample pathology report
- Vaginal cuff, biopsy:
- Myofibroblastic proliferation, favor postoperative spindle cell nodule (see comment)
- Comment: The patient’s recent history of vaginal hysterectomy is noted. Microscopic examination reveals loose fascicles of spindle cells with open chromatin and brisk mitoses. The spindle cells are positive for SMA (diffuse) and desmin (focal) but negative for cytokeratin and S100. In this clinical context, the morphological and immunophenotypic findings are most consistent with a diagnosis of postoperative spindle cell nodule. This is regarded as a benign diagnosis. If there is clinical concern for a more significant process, a fluorescence in situ hybridization assay for USP6 rearrangement could be performed to further substantiate the diagnosis. Early regrowth (i.e., within a few weeks) of postoperative spindle cell nodule has been reported but is not associated with adverse outcomes.
Differential diagnosis
- Leiomyosarcoma:
- Boxcar shaped nuclei with cytologic atypia (nuclear pleomorphism or hyperchromasia)
- Atypical mitoses and tumor necrosis is often present
- Not associated with the postsurgical setting
- Frequent alterations of TP53, ATRX, Rb and CDKN2A; USP6 rearrangement is absent
- Nodular fasciitis:
- Typically occurs in subcutaneous tissue of the upper extremities, trunk, and head and neck; rare at mucosal sites
- History of trauma in a minority of cases
- USP6 rearrangement characteristic of nodular fasciitis may also be encountered in postoperative spindle cell nodule (Histopathology 2023;82:587)
- Inflammatory myofibroblastic tumor (Arch Pathol Lab Med 2019;143:122):
- Most common site in the female genital tract is the uterine corpus, with only rare vulvovaginal involvement
- Characteristic admixture of myxoid, fascicular (leiomyoma-like) and sclerotic morphologies
- ALK rearrangements are characteristic
- ALK immunohistochemistry is positive
- Not associated with the postsurgical setting
- Kaposi sarcoma:
Board review style question #1
A 45 year old woman undergoes endometrial curettage and presents 3 weeks later with a 3.5 cm firm polypoid mass in the endocervix. What is the best diagnosis?
- Kaposi sarcoma
- Leiomyosarcoma
- Nodular fasciitis
- Postoperative spindle cell nodule
Board review style answer #1
D. Postoperative spindle cell nodule. The characteristic postsurgical clinical presentation and the morphologic features of fascicles of spindled cells with intervening vasculature make postoperative spindle cell nodule the correct diagnosis. Answer C is incorrect because nodular fasciitis rarely occurs in mucosal sites following a history of surgical intervention. Answer A is incorrect because Kaposi sarcoma is usually seen in immunocompromised or elderly patients. Answer B is incorrect because the characteristic cytologic atypia is not seen in this case and a fast growing, postsurgical mass is not typical of a sarcoma.
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Reference: Postoperative spindle cell nodule
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Reference: Postoperative spindle cell nodule
