Testis and epididymis
Paratesticular tumors

Author: Swapnil U. Rane, M.D. (see Authors page)
Editorial Board review: Debra Zynger, M.D.

Revised: 1 September 2015, last major update August 2015

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: Liposarcoma [title] testis
  • Rare; mean 63 years, range 41 to 87 years, but younger patients have been reported
  • Most common malignant tumor involving the spermatic cord (46%) (Urol Oncol 2014;32:52)
  • Paratesticular liposarcomas account for ~12% of all liposarcomas
  • Well differentiated tumors tend to recur, often late, yet have a good outcome; dedifferentiated tumors have metastatic potential
  • Sites
  • Usually arise from spermatic cord; also testicular tunica; rarely epididymis
  • Pathophysiology / Etiology
  • Recurrent molecular abnormalities have been detected in liposarcomas, which differ between each subtype
  • Well differentiated liposarcoma is characterized by the presence of amplification involving 12q13-q15, which can be identified using FISH or CGH
  • Myxoid liposarcoma is characterized by the presence of t(12;16)(q13;p11), which results in the FUS-CHOP gene fusion that is present in over 95% of cases
    • Most often, the amino terminal domain of FUS (also known as TLS) is fused to C/EBP homologous protein (CHOP, also known as DDIT3 or GADD153)
    • In rare cases, an alternative translocation event is found, t(12;22)(q13;q12), that results in formation of the novel fusion oncogene where EWS takes the place of FUS
    • RET, IGF1R and IGF2 are highly expressed in MLPS and promote cell survival through both the PI3K/Akt and Ras-Raf-ERK/MAPK pathways (Hum Pathol 2009;40:1244, Nat Clin Pract Oncol 2007;4:591) and represent potential therapeutic targets
  • Pleomorphic liposarcoma shows complex chromosomal abnormalities with gains in 1p, 1q21-q32,2q, 3p, 3q, 5p12-p15, 5q, 6p21, 7p, 7q22 and losses involving 1q, 2q, 3p, 4q, 10q, 11q, 12p13, 13q14, 13q21-qter, 13q23-24
  • Clinical Features
  • Painless scrotal mass of longstanding duration is the most common presentation
  • Rarely is of recent duration
  • May present as an inguinal hernia, hydrocele, hematocoele or other testicular tumor
  • Diagnosis
  • Diagnosis requires histological examination
  • Clinical differentiation from other testicular and paratesticular sarcomas is not possible
  • Laboratory
  • No specific laboratory abnormality is known
  • Serum markers for germ cell tumors and sex cord tumors are negative
  • Prognostic Factors
  • Recurrence of well differentiated paratesticular liposarcoma after complete resection is extremely rare (Malays J Med Sci 2013;20:95)
    • Recurrence rate is < 10% when resection margin is 10mm or greater
    • Risk factors for local recurrence/progression:
      • High grade tumor morphology
      • Large tumor size (>5cm)
      • Inadequate/suboptimal resection
  • Case Reports
  • 23 year old man with paratesticular myxoid liposarcoma (Rare Tumors 2010;2:e23)
  • 46 year old man with paratesticular myxoid / round cell liposarcoma (Pathol Res Pract 2013;209:124)
  • 50 year old man with recurrence of paratesticular liposarcoma (World J Surg Oncol 2014;12:276)
  • 50 year old man with paratesticular liposarcoma masquerading as a testicular tumor (J Clin Diagn Res 2014;8:165)
  • 65 year old man with bilateral paratesticular liposarcoma (J Surg Tech Case Rep 2014;6:15)
  • 77 year old man with paratesticular dedifferentiated liposarcoma with leiomyosarcomatous differentiation (Diagn Pathol 2013;8:142)
  • Mixed paratesticular liposarcoma with osteosarcoma elements (Clin Transl Oncol 2010;12:148)
  • Well differentiated inflammatory liposarcoma (Am J Surg Pathol 1997;21:518)
  • Dedifferentiated liposarcoma (Am J Surg Pathol 1994;18:1213)
  • Treatment
  • Usual treatment is orchidectomy through inguinal approach, with adequate margins
  • Elective inguinal node dissection is not indicated
  • Cases with a margin <10 mm or with residual tumor may benefit from radiotherapy; liposarcoma is radiosensitive, and the well differentiated subtype is most sensitive
  • Radiotherapy also useful for unresectable cases
  • Role of chemotherapy (ex: doxorubicin) is debated; no clear benefit has been shown
  • Surgical excision is also the cornerstone of management of recurrent cases
  • Clinical Images
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    Non homogeneous right scrotal mass

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    No evidence of tissue infiltration

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    Large heterogenous extratesticular mass

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    Scrotal mass at presentation

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    Tumor after chemotherapy

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    CT of paratesticular liposarcoma presenting as hernia

    Gross Description
  • Tumors are usually large, appear to be relatively circumscribed
  • Cut surface may be yellow, fatty with interspersed fibrous septae, or may be uniformly firm and white
  • Areas of necrosis and hemorrhage may be seen in high grade tumors
  • Gross Images
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    Tumor mass

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    Yellow and myxoid areas

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    White-yellow to red-brown cut surface, marked necrosis

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    Right paratesticular mass with solid, yellow-white, fatty, myxoid areas

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    Grossly firm tumor

    Micro Description
  • Mature adipocytes, atypical spindle cells and multivacuolated lipoblasts embedded in a loose myxoid to dense fibrous stroma
  • All variants of liposarcoma may be seen; well differentiated or dedifferentiated liposarcomas are most common
  • Heterologous leiomyosarcomatous or osteosarcomatous differentiation (Am J Surg Pathol 2002;26:742) and osseous metaplasia (Case Rep Urol 2015;2015:965876) have been reported, but their presence does not appear to affect prognosis
  • Pleomorphic liposarcoma accounts for <5% of cases, and is characterized by MFH-like histology with a disorderly pattern, pleomorphic cells, multinucleated bizarre giant cells and lipoblasts
  • Giant lipoblasts have enlarged globular or angular hyperchromatic nuclei
  • Other variants have also been reported
  • Micro Images
    Well differentiated liposarcoma
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    Atypical spindle cells and lipoblasts

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    Mature adipocytes and lipoblasts

    Well differentiated with dedifferentiated component
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    Hypercellular stroma with atypical adipocytes

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    Atypical adipocytes with enlarged nuclei

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    Dedifferentiated liposarcoma

    Dedifferentiated with leiomyosarcomatous component
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    MDM2+, CDK4+,
    alpha smooth muscle actin+, desmin+

    Myxoid liposarcoma
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    Lipoblasts contain lipid vacuoles

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    Plexiform arrangement of capillaries

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    Various images

    Positive Stains
  • MDM2, CDK4 (usually negative in myxoid/round cell and spindle subtypes)
  • S100
  • Heterologous elements may show positivity for desmin, actin, etc., based on the differentiation and dedifferetiated tumors have variable reactivity
  • STAT6 may rarely be positive (reported in dedifferentiated liposarcoma)
  • Negative Stains
  • HMB45, CD34, actin, keratins, desmin are negative in the lipoblasts
  • Differential Diagnosis
  • Aggressive angiomyxoma
  • Angiomyolipoma: HMB45 positive
  • Embryonal rhabdomyosarcoma
  • Fibromatosis: resembles sclerosing liposarcoma but is more cellular, has no atypia, has denser collagen and is CD34 negative
  • Inflammatory fibrous pseudotumor: resembles inflammatory liposarcoma but has bland spindle cells
  • Inflammatory myofibroblastic tumor
  • Lipoma: mimics well differentiated liposarcoma but has no atypical adipocytes and no lipoblasts
  • Lymphoma: mimics inflammatory liposarcoma but has monoclonal lymphocytes (usually B cell not T cell)
  • Primary retroperitoneal sarcoma extension
  • Sclerosing lipogranuloma