A 14-year-old boy presents as a new patient to your practice. While conducting your physical exam, you observe the findings depicted in Figures A and B. Which of the following additional findings would most likely be found in this patient?

A white tuft of scalp hair since birth

A family history of seizures and intellectual disability

A 24-year-old man comes to the physician because of 2 episodes of bleeding from the rectum over the past month. The patient’s father died of colon cancer at the age of 42. The patient has no history of any serious illness and takes no medications. He does not smoke. His vital signs are within normal limits. Physical examination shows a small hard mass over the right mandible that is nontender and fixed to the underlying bone. A similarly hard and painless 5 × 5 mass is palpated over the rectus abdominis muscle. On examination of the rectum, a polypoid mass is palpated at fingertip. Proctosigmoidoscopy shows numerous polyps. Which of the following best explains these findings?

Familial polyposis of the colon

A 67-year-old man presents with pain in both legs. He says the pain is intermittent in nature and has been present for approximately 6 months. The pain increases with walking, especially downhill, and prolonged standing. It is relieved by lying down and leaning forward. Past medical history is significant for type 2 diabetes mellitus, hypercholesterolemia, and osteoarthritis. The patient reports a 56-pack-year history but denies any alcohol or recreational drug use. His vital signs include: blood pressure 142/88 mm Hg, pulse 88/min, respiratory rate 14/min, temperature 37°C (98.6°F). On physical examination, the patient is alert and oriented. Muscle strength is 5/5 in his upper and lower extremities bilaterally. Babinski and Romberg tests are negative. Pulses measure 2+ in upper and lower extremities bilaterally. Which of the following is the next best step in the management of this patient?

CT angiography of the lower extremities

Epidural corticosteroid injection

A 43-year-old man is brought to the emergency department 40 minutes after falling off a 10-foot ladder. He has severe pain and swelling of his right ankle and is unable to walk. He did not lose consciousness after the fall. He has no nausea. He appears uncomfortable. His temperature is 37°C (98.6°F), pulse is 98/min, respirations are 16/min, and blood pressure is 110/80 mm Hg. He is alert and oriented to person, place, and time. Examination shows multiple abrasions over both lower extremities. There is swelling and tenderness of the right ankle; range of motion is limited by pain. The remainder of the examination shows no abnormalities. An x-ray of the ankle shows an extra-articular calcaneal fracture. Intravenous analgesia is administered. Which of the following is the most appropriate next step in the management of this patient?

Short leg splint and orthopedic consultation

Broad-spectrum antibiotic therapy

Open reduction and internal fixation

Soft tissue tumors for USMLE Step 2 CK: High-Yield Pathology Lessons

Soft Tissue Tumors - The Body's Lumps

Mesenchymal origin; classified by tissue type (fat, muscle, vascular).
Benign Tumors: "-oma"
- Lipoma: Most common soft tissue tumor in adults. Mobile, soft, painless.
- Rhabdomyoma: Benign skeletal muscle tumor. Often in the heart (associated with Tuberous Sclerosis).
Malignant Tumors: "-sarcoma"
- Liposarcoma: Malignant fat tumor; lipoblasts are key.
- Rhabdomyosarcoma: Most common soft tissue sarcoma in children.

⭐ Rhabdomyosarcoma often presents as a "grape-like" mass (sarcoma botryoides) in the vagina or bladder of young girls.

Benign Tumors - Mostly Harmless

Benign soft tissue tumors are common, slow-growing, well-differentiated masses with low metastatic potential. Management is typically surgical excision if symptomatic.

Tumor	Tissue of Origin	Key Features
Lipoma	Adipose Tissue	Most common soft tissue tumor in adults. Soft, mobile, painless.
Fibroma	Fibroblastic	Firm mass. Ovarian fibromas can cause Meigs syndrome.
Leiomyoma	Smooth Muscle	Most common in the uterus ("fibroids"). Whorled pattern of smooth muscle.
Rhabdomyoma	Skeletal Muscle	Rare. Cardiac type associated with Tuberous Sclerosis.
Hemangioma	Blood Vessels	Common in infancy (strawberry hemangioma); often regress spontaneously.

Malignant Sarcomas - The Real Villains

General Features: Deep-seated, large (>5 cm), aggressive tumors. Tend to spread hematogenously (lungs are a common site of metastasis).
Liposarcoma:
- Most common sarcoma in adults (40-60 years).
- Key feature: Lipoblasts (cells with vacuolated, lipid-rich cytoplasm and a scalloped nucleus).
- Well-differentiated type is associated with MDM2 amplification.
Rhabdomyosarcoma:
- Most common soft tissue sarcoma in children (<15 years).
- Key cell: Rhabdomyoblast (tadpole or strap cells; may show cross-striations). Stains for desmin, myogenin.
- Embryonal subtype is most common; Alveolar subtype has t(2;13) or t(1;13) translocations and a worse prognosis.
Synovial Sarcoma:
- Typically affects adolescents and young adults (15-40 years), often near large joints (e.g., knee).
- ⭐ Pathognomonic finding: t(X;18) translocation, resulting in an SS18-SSX fusion protein.

Diagnosis & Genetics - Cracking the Code

Initial Dx: H&P, imaging (MRI is key).
Tissue is the Issue: Biopsy (core needle > incisional/excisional) is mandatory before treatment.
Microscopy: Spindle cells, pleomorphism, mitotic activity.
Immunohistochemistry (IHC): Crucial for lineage.
- Desmin: Muscle (rhabdomyo-)
- S100: Neural (MPNST)
- CD34: Vascular (angiosarcoma), GIST

⭐ Synovial Sarcoma: Characterized by the t(X;18) translocation, creating an SS18-SSX fusion gene.

Lipoma is the most common benign soft tissue tumor in adults; liposarcoma is the most common malignant, linked to MDM2 amplification.

Rhabdomyosarcoma is the most frequent soft tissue sarcoma in children, typically the embryonal type in the head, neck, or genitourinary tract.

Nodular fasciitis mimics sarcoma with its rapid growth and high cellularity but is a benign, self-limiting process.

Synovial sarcoma, despite its name, is unrelated to synovium and shows a characteristic t(X;18) translocation.

Desmoid fibromatosis is locally aggressive but non-metastatic, often associated with APC/β-catenin pathway mutations.

Continue reading on Oncourse

CONTINUE READING — FREE

or get the app

App Store|Google Play

Soft tissue tumors