What should be done for a suddenly enlarged, tender, round, non-erythematous, firm, and movable sternal mass?

Management of a Suddenly Enlarged, Tender Sternal Mass

A suddenly enlarged, tender, round, non-erythematous, firm, and movable sternal mass in a young patient (under 4 years old) most likely represents self-limiting sternal tumor of childhood (SELSTOC) and should be managed with close observation and serial physical examinations over 1-6 months, avoiding invasive procedures unless the mass fails to regress. 1

Initial Clinical Assessment

Age-Based Differential Diagnosis

For children under 4 years of age:

• The sudden increase in size with tenderness strongly suggests SELSTOC, a benign aseptic inflammatory condition that presents as a rapidly growing sternal mass in young children (median age 16 months, range 7-50 months) 1
• SELSTOC characteristically presents as a solid, pre-sternal or para-sternal mass with median diameter of 3 cm (range 1-4.5 cm), often with local pain and sometimes with red/blue skin discoloration 1
• The movable, firm nature without erythema fits the typical presentation of SELSTOC 1

For adults or older patients:

• Primary malignant tumors (chondrosarcoma most common, followed by osteosarcoma) typically present as a mass, with half of patients also experiencing sternal pain 2
• Metastatic disease should be considered, particularly in patients with known malignancy history 3

Recommended Management Algorithm

For Suspected SELSTOC (Young Children)

Adopt a wait-and-see approach with close follow-up:

• Perform serial physical examinations weekly for the first month 1
• The mass should decrease in size within 1 month and completely disappear on physical examination within 6 months 1
• Antibiotics are not necessary, as tumors resolve equally well with or without antibiotic treatment 1

Imaging if performed (though not mandatory for typical presentations):

• If imaging is obtained, expect to see dumbbell-shaped lesions extending behind the sternal bone, involving cartilage, with increased distance between ossification centers 1
• CT may show widening of the synchondrosis between sternal elements 4

Avoid invasive procedures initially:

• Histopathology, when performed, typically shows nonspecific chronic or acute inflammation 1
• Laboratory infection parameters are usually not elevated or only slightly raised, and microbiologic cultures are negative 1
• Invasive diagnostic interventions and unnecessary treatment should be prevented by this conservative approach 1

For Adults or Atypical Presentations

Immediate imaging is required:

• Obtain CT of the chest to characterize the mass and assess for pulmonary metastases 5
• MRI provides the most accurate information for diagnosis and surgical planning for soft tissue tumors 5
• Look for irregular, multilobulated, heterogeneously enhancing masses with intralesional calcifications, which suggest sarcoma 5

Tissue diagnosis:

• Percutaneous core needle biopsy is the standard approach, with multiple cores taken under image guidance 5
• Plan the biopsy tract so it can be safely removed during definitive surgery 5
• Fine needle aspiration is not recommended as a primary diagnostic modality 5

Specialist referral:

• Refer to a specialist sarcoma multidisciplinary team (MDT) for any suspicious mass in adults 5
• Referral should occur within 2 weeks via a suspected cancer pathway 5

Key Clinical Pitfalls to Avoid

Do not perform invasive biopsies in young children with typical SELSTOC presentation:

• The characteristic rapid growth, tenderness, and age profile (under 4 years) should prompt observation rather than immediate biopsy 1
• Unnecessary invasive procedures expose children to procedural risks without benefit 1

Do not delay specialist referral in adults:

• Primary sternal sarcomas, though uncommon, are potentially curable by wide surgical excision when diagnosed early 2
• Chondrosarcomas have an 80% 5-year survival with resection, while high-grade sarcomas have only 7% survival, emphasizing the importance of early diagnosis and treatment 2

Do not rely solely on clinical examination in adults:

• Half of patients with malignant sternal tumors present with mass alone, without pain, making clinical assessment insufficient 2
• Imaging is essential to characterize the lesion and plan appropriate management 5

Indications for Urgent Intervention

Proceed to immediate imaging and biopsy if:

• The patient is an adult or older child (over 4 years) 1, 2
• The mass fails to decrease in size within 1 month in a young child 1
• There are concerning features such as fixed (non-movable) mass, skin ulceration, or systemic symptoms suggesting malignancy 5
• There is known history of malignancy, as metastatic disease to the sternum occurs and requires different management 3