HPI
• A 32 yo G2P2 woman presents to her PCP
because of a lump that she felt on her lower
belly. It is not painful but she thinks it has been
growing in size over the past few months. She is
concerned because there is a family history of
colon cancer. She denies change in weight,
fevers/chills/night sweats, nausea/vomitting,
abdominal pain, and change in bowel
movements.
• What else would you like to know?
PMH
• Medical Hx: C-section (2007, 2009), umbilical
hernia repair (2011)
• Family Hx: Colon cancer (father, uncle,
grandmother)
• Social: Married with 2 children, kindergarten
teacher
• What is your differential diagnosis?
DDx
• Scar tissue (reactive fibrosis)
• Soft tissue tumor: desmoid, fibrosarcoma,
lymphoma, neurofibroma
• Hemangioma
• Hernia
• What do you want to do next?
Physical Exam
•
•
•
•
Vitals: BP 120/70, T 97.8, HR 70, RR 14
General: Patient is comfortable and cooperative
HEENT, CV, Respiratory, Neuro, and Psych Exams: wnl
Abdominal: bowel sounds present, no
rebound/guarding, soft, no pain to palpation, firm and
mobile mass in LLQ
• Skin: warm, dry, no discoloration or rashes present
• What tests do you want to order?
Tests
• CBC – normal
– Check WBC to rule out lymphoma
• Pregnancy test – negative
• Imaging to evaluate mass:
– Ultrasound – easy and inexpensive
– CT or MRI – depending on u/s results
• Biopsy of mass for diagnosis
Abdominal Ultrasound
• Homogenous hypoechoic (dark) mass
Abdominal CT
• Well-circumscribed mass, usually homogenous
– White arrow
Abdominal MRI
• Well-circumscribed mass
– White arrow
Histology
• Spindle-shaped cells surrounded by collagen
Gross Specimen
• Well-defined capsule with collagen and fibrous
sections
Overview of Desmoid Tumor
• “Aggressive fibromatosis”
• Fibrous, well-differentiated neoplasm originating
from myofibroblasts
• Mutation of beta catenin
• Sporadic or associated with Gardner’s Syndrome
Overview of Desmoid Tumor
• Can arise in any skeletal muscle
– Often the rectus abdominis
• Local infiltration can cause deformities and
significant obstruction or compression
• Does not metastasize
• Histologically benign
Hallmarks of Desmoid Tumor
• Benign histology  bland fibroblasts
Hallmarks of Desmoid Tumor
• Post-partum or history of abdominal surgery
• Females > Men (~ 2:1)
• Typical patient is between 20 – 40 years old
– Can occur in children and elderly
Associated Diseases
• Gardner Syndrome
– Characterized by numerous colorectal polyps,
osteomas, and soft tissue neoplasms
– Autosomal dominant
– 10-15% have desmoid tumors
• Bi-allelic APC mutation (“two-hit” hypothesis)
– Subset of Familial Adenomatous Polyposis (FAP)
Treatment
1. Surgery
– Surgical removal with negative margins is first-line
treatment
– Positive margins increase likelihood of recurrence
2. Radiation
– adjunct or sole treatment
3. Chemotherapy
– recurrent desmoid tumors
Pearls
• Desmoid tumor itself is benign but infiltration
can cause morbidity
• Typical patient is post-partum woman in her
30s or female with previous abdominal
surgery
• Recurrence rate is high (70%)
• Associated with Gardner’s Syndrome
Pearls
• American Cancer Society Colon Cancer
Screening Guidelines
– In general: colonoscopy at age 50
– Family Hx: colonoscopy at age 40 or 10 years
earlier than youngest relative at age of diagnosis
– FAP: annual flexible sigmoidoscopy starting at age
10 years and consider colectomy
Summary
• The patient is referred to a surgeon for
removal of the desmoid tumor
• Due to her strong family history of colon
cancer, she is scheduled for a colonoscopy and
will consider being tested for the APC
mutation so that she will know if her children
are at risk