Prostate gland & seminal vesicles

Acinar / ductal adenocarcinoma

Sarcomatoid carcinoma



Topic Completed: 18 May 2021

Minor changes: 18 May 2021

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PubMed search: Sarcomatoid carcinoma[TIAB] prostate

Sami Talibi, M.D.
Steven Christopher Smith, M.D., Ph.D.
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Cite this page: Talibi S, Smith SC. Sarcomatoid carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/prostatecarcinosarcoma.html. Accessed October 24th, 2021.
Definition / general
  • WHO recognized variant subtype of prostatic adenocarcinoma
  • Malignant monophasic or biphasic neoplasm including a spindle cell or pleomorphic sarcomatoid component
  • Represents dedifferentiation from (usually high grade acinar) prostatic adenocarcinoma
  • Clinical, histologic, immunophenotypic or molecular evidence of origin from prostatic adenocarcinoma
Essential features
  • Malignant sarcomatoid neoplasm, usually admixed with recognizable prostatic adenocarcinoma but rarely monophasic
  • Monophasic cases have history, immunophenotypic or molecular evidence relating the sarcomatoid malignancy to prostatic adenocarcinoma
  • Most cases are associated with prior radiotherapy or hormone therapy
  • Usually clinically aggressive, high stage, poor prognosis
Terminology
  • Formerly carcinosarcoma
ICD coding
  • ICD-O: 8572/3 - adenocarcinoma with spindle cell metaplasia
  • ICD-10: C61 - malignant neoplasm of prostate
  • ICD-11: 2C82 & XH2QL8 - malignant neoplasms of prostate and adenocarcinoma with spindle cell metaplasia
Epidemiology
Sites
  • Prostate gland
  • Frequent invasion of the bladder
  • Systemic metastases to lungs and bone
Pathophysiology
  • Arises via dedifferentiation from precursor conventional prostatic adenocarcinoma
  • Preexisting carcinoma diagnosed may be low grade (grade group 1, ~50%) or higher (grade group 2, ~50%)
  • Molecular features shared between sarcomatoid and carcinomatous component (Histopathology 2015;66:898)
    • ERG rearrangements shared between components
Etiology
  • Risk factors related to precursor conventional prostatic adenocarcinoma
  • Strong association with prior hormone or radiation therapy
Clinical features
  • Organ confined disease has best prognosis
    • Definitive treatment recommended
  • Increased aggression in locally advanced and metastatic disease (Urology 2015;86:539)
  • Documented metastases most often show adenocarcinomatous component
Diagnosis
  • Biopsy, transurethral resection or prostatectomy specimens
Laboratory
  • PSA elevated in some cases
Radiology description
  • Staging by MRI, CT and bone scan
Radiology images

Contributed by Steven Christopher Smith, M.D., Ph.D.

Liver metastases

Prognostic factors
  • Median overall survival < 1 year
  • Prognosis (overall survival) has been related to a modified staging system (Urology 2015;86:539)
    • Organ confined: ≥ 5 years
    • Locally advanced / bladder invasion: 9 months
    • Metastatic disease: 7 months
Case reports
Treatment
  • Standard treatments not established
  • Localized sarcomatoid carcinoma treated by radical prostatectomy or external beam radiotherapy
Gross description
Microscopic (histologic) description
  • Overall criteria, a tumor showing either:
    • Biphasic admixture of malignant sarcomatoid component with recognizable conventional prostatic adenocarcinoma
    • Monophasic sarcomatoid tumor with historical, immunohistochemical or molecular evidence relating it to prostatic adenocarcinoma
  • Sarcomatoid component
    • Most commonly a nondescript spindle cell appearance
    • Hypercellular fusiform cells
    • Storiform, fascicular or patternless architecture
    • High grade with large hyperchromatic nuclei
    • Frequent mitotic activity and necrosis
    • May resemble high grade pleomorphic sarcoma with giant cells and bizarre nuclei
    • Subset with heterologous sarcoma patterns with differentiation toward other mesenchymal lineages
      • Osteosarcoma (most common)
      • Rhabdomyosarcoma
      • Chondrosarcoma
  • Carcinomatous component
    • Most commonly high grade acinar adenocarcinoma
    • Uncommonly: foamy gland, ductal, adenosquamous, signet cell presentations
    • Individual polygonal or epithelioid cells may be present within the sarcomatoid component
    • Adenosquamous small cell components may be present
  • Monophasic spindle cell morphology
    • History documents a prior acinar adenocarcinoma
    • Immunohistochemical evidence of epithelial differentiation
      • Expression of keratins, prostate lineage markers
    • Molecular evidence of prostatic origin
      • Rearrangements of ERG of other ETS family proto-oncogenic transcription factors
  • Reference: Am J Surg Pathol 2006;30:1316
Microscopic (histologic) images

Contributed by Steven Christopher Smith, M.D., Ph.D.
Transurethral resection

Transurethral resection

Biphasic histology

Biphasic histology

Monophasic sarcomatoid carcinoma

Monophasic sarcomatoid carcinoma

Adenosquamous component

Adenosquamous component

Subtle epithelial component

Subtle epithelial component

Focal epithelial differentiation

Focal epithelial differentiation


Heterologous chondrosarcoma pattern

Heterologous chondrosarcoma pattern

Heterologous osteosarcoma pattern

Heterologous osteosarcoma pattern

Heterologous rhabdomyosarcoma pattern

Heterologous rhabdomyosarcoma pattern

Pleomorphic sarcomatoid pattern

Pleomorphic sarcomatoid pattern

Keratin positivity

Keratin positivity

ERG positivity

ERG positivity

Immunohistochemistry
Molecular / cytogenetics description
Sample pathology report
  • Prostate gland, transurethral resection:
    • Sarcomatoid carcinoma of the prostate, involving 10 of 15 tissue fragments resected and ~75% of the tissue sampled (see comment)
    • Focal heterologous osteosarcomatous differentiation is present
    • Associated prostatic adenocarcinoma, grade group 5 (Gleason score 4+5=9)
    • Comment: Sarcomatoid carcinoma of the prostate is an aggressive malignancy where carcinoma undergoes dedifferentiation to a sarcomatous component demonstrating variable but usually spindle cell or pleomorphic morphology. Many cases are associated with previous hormone or radiotherapy for prostatic adenocarcinoma.
Differential diagnosis
  • Prostatic stromal sarcoma:
  • Prostatic leiomyosarcoma:
    • No admixed (or prior) adenocarcinomatous component
    • Usually more fascicular spindle cell growth
    • Elongated cells, eosinophilic cytoplasm, cigar shaped nuclei
    • Diffuse SMA, desmin positivity
    • Lacks keratin, p63, prostate marker expression
  • Prostatic solitary fibrous tumor:
    • No admixed (or prior) adenocarcinomas component
    • More cytologically uniform tumor with small spindled to polygonal cells
    • Uniform, angulated or carrot shaped nuclei
    • Patternless architecture, staghorn thin walled vasculature
    • Diffuse expression of CD34 and STAT6
    • Lacks keratin, p63, prostate marker expression
Board review style question #1

An 81 year old man presents with an obstructing urethral mass and on CT scan imaging is shown to have recent development of a 6 cm obstructing mass arising from the prostate, compressing and displacing the urethra. Transurethral resection demonstrates a spindle cell tumor with brisk mitotic activity and nuclear pleomorphism but no prostatic or urothelial carcinoma is visible. What additional findings would argue most strongly for diagnosis of sarcomatoid carcinoma of the prostate?

  1. Dense, fascicular growth, diffuse expression of desmin and SMA
  2. Focal desmin positivity, diffuse vimentin positivity
  3. Patchy high molecular weight keratin expression in subsets of the spindle cells, history of high grade prostatic adenocarcinoma treated by androgen deprivation therapy and pelvic radiotherapy 5 years previously
  4. Staghorn vasculature, CD34 and STAT6 expression
Board review style answer #1
C. Patchy high molecular weight keratin expression in subsets of the spindle cells, history of high grade prostatic adenocarcinoma treated by androgen deprivation therapy and pelvic radiotherapy 5 years previously

Comment Here

Reference: Sarcomatoid carcinoma
Board review style question #2
A 48 year old man presents with an obstructing mass arising in the prostate and bladder neck. It demonstrates dense, organized fascicular growth of fusiform cells with dense eosinophilic cytoplasm and elongated nuclei. What features would support consideration of a prostatic leiomyosarcoma?

  1. Positive rearrangement of the ERG locus by FISH
  2. Scattered admixed glands with cytoplasmic atypia; focal p63 and CK903 / 34 beta E12 expression in scattered spindle cells
  3. Strong, diffuse expression of SMA and desmin
  4. Thin walled ramifying vasculature, nuclear STAT6 positivity
Board review style answer #2
C. Strong, diffuse expression of SMA and desmin

Comment Here

Reference: Sarcomatoid carcinoma
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