Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Soft Tissue Tumors (Sarcomas)


Soft tissue tumors are among the most difficult neoplasms to diagnose. Often special studies (e.g., immunoperoxidase studies, fluorescence in situ hybridization [FISH], or cytogenetics) are required for the appropriate classification of these tumors and for reliable separation from carcinomas, melanomas, and lymphomas.

RELEVANT CLINICAL HISTORY (IN ADDITION TO AGE AND GENDER)

See Table 28.1 .

Table 28.1
RELEVANT CLINICAL HISTORY
HISTORY RELEVANT TO ALL SPECIMENS HISTORY RELEVANT FOR SARCOMA SPECIMENS
Organ/tissue resected or biopsied Location and depth of mass
Purpose of the procedure Involvement of soft tissue or bone
Gross appearance of the organ/tissue/lesion sampled Rate of growth (duration of lesion)
Any unusual features of the clinical presentation Presenting symptoms and signs
Any unusual features of the gross appearance Appearance on imaging
Prior surgery/biopsies - results
Prior malignancy Family history of a syndrome predisposing to tumors (e.g., Li-Fraumeni syndrome, familial retinoblastoma syndrome)
Prior treatment (radiation therapy, chemotherapy, drug use that can change the histologic appearance of tissues)
Prior history of radiation therapy
Compromised immune system

Biopsies

Biopsies are usually performed to make decisions about the use of preoperative therapy and the necessary extent of surgery to obtain adequate margins. Either incisional or needle biopsies are used. An incisional biopsy removes a portion of the tumor for diagnosis without the intent to remove the entire tumor. It may not be possible to provide a specific diagnosis or grade based on very small specimens.

PROCESSING THE SPECIMEN

  • 1.

    Relevant clinical history should be provided or obtained to establish a preoperative differential diagnosis (including patient gender, age, location and depth of mass, involvement of soft tissue and/or bone, and prior history of malignancies). The most likely diagnosis aids in deciding how to apportion limited amounts of lesional tissue.

  • 2.

    Describe the specimen including type (needle, incisional), size, color, and necrosis or hemorrhage. Indicate what proportion of the specimen appears to be lesional (typically firm and white) and nonlesional (e.g., fibrous tissue interminged with adipose tissue).

  • 3.

    Very small or very heterogeneous specimens (i.e., little tissue is available and viable tumor is difficult to identify grossly) are fixed in formalin and submitted in entirety.

  • Larger specimens should be apportioned for special studies if lesional tissue can be identified.

  • In selected cases, examination of a frozen section or a cytologic preparation may be helpful to narrow the differential diagnosis and guide apportionment of limited tissue.

SPECIAL STUDIES

Formalin: Formalin-fixed tissue remains the cornerstone of diagnosis. Sufficient representative samples should be fixed in formalin before submitting tissue for special studies. Fluorescence in situ hybridization (FISH) and the majority of molecular studies can be performed on routinely fixed and paraffin embedded tissue.

Frozen tissue: One or more 1 cm 3 fragments are optimal. Smaller samples are acceptable if the specimen is limited. The tissue is cut into 0.2 cm fragments and stored at -70°C.The tissue can be used for molecular analysis (e.g., analysis of DNA or RNA by FISH, Southern blotting, polymerase chain reaction [PCR], or reverse transcription PCR [RT-PCR]). Frozen tissue may be required for some clinical treatment protocols.

Cytogenetics: It is helpful to save tissue for cytogenetics if sarcoma is suspected clinically and there is a sufficient sample. Cytogenetics is a very useful technique for classifying some tumors, but it may require a large volume of tissue that cannot be examined histologically. The equivalent amount of two needle biopsies may be sufficient for highly cellular tumors, but at least 1 cm 3 of tumor is preferred. Many diagnostic genetic alterations can be identified on fixed tissue sections using in situ hybridization and DNA sequencing.

Lipomas

Lipomas are the most common benign soft tissue tumors in adults and are typically diagnosed between the ages of 40 and 60 years. They may occur in subcutaneous tissue or be located more deeply within or adjacent to muscle. The findings on magnetic resonance (MRI) imaging can be very helpful to support a benign diagnosis.

Lipomas are often removed for cosmetic reasons. Although rare (~1% of lesions) malignancy must always be excluded. The likelihood of malignancy is increased if any of the following features are present:

  • Large size (over 5 cm)

  • Infiltration into surrounding tissues

  • Location in deep tissues, retroperitoneum, or near the spermatic cord

  • History of recurrence

  • Unusual gross appearance – any appearance other than apparently normal fat (e.g., white or cream colored, homogeneous, firm, fibrotic areas, attached tissues)

  • Unusual appearance on MRI - heterogenous signal intensity, post-contrast enhancement, necrosis

Cord lipomas are found in about 22% of men undergoing inguinal hernia repair. Whether all of these lesions are true neoplasms or if some are anatomic variants is debated. Liposarcomas can involve the inguinal canal either due to extension from a retroperitoneal tumor or can directly arise within the inguinal canal. There have been 200 cases of liposarcomas of the spermatic cord, and some of these were incidental findings during a hernia operation. , However, in two studies, incidental liposarcoma was detected in ≤0.1% of hernia sac operations. , The four patients in these studies with liposarcoma were older than the average patient with cord lipoma (49 to 78 years versus 35 years), and the tumors were larger than the average lipoma (8 to 13 cm versus 5.5 cm).

Lipomas are usually enucleated without removal of the adjacent tissue. Thus, the lesion is often fragmented. There is no need to ink these specimens as the lesion is present at the margin and margins are irrelevant for the vast majority of benign lesions.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts