Thigh Mass in a Young Child
A 9-year-old African American female presented with a painless left thigh swelling first noted 3 weeks prior, which had been slightly increasing in size over. On the day prior to presentation, she also developed nonradiating, left groin pain that was exacerbated by flexion at the hip. She had no difficulty walking and denied any skin changes.
History
The patient denied any associated fever, chills, unintentional weight change, bone pain, upper respiratory infection symptoms, nausea, vomiting, diarrhea, joint pain, or new rashes. She had not sustained any identifiable trauma to the left lower extremity. The family kept no pets at home and had not travelled recently.
Her past medical history was unremarkable and there was no family history of deep-seated skin infections, muscle, or bleeding disorders, or of childhood cancers.
Physical Examination
The patient was afebrile with vitals within normal limits for her age. Her lymphatic exam was unremarkable. There were no skin changes in the painful area of the groin. She had full active and passive range of motion at the hips bilaterally and walked with a normal gait.
On physical examination, there was a 7 cm x 7.5 cm elongated, firm, fixed, soft tissue mass on the anteromedial aspect of the left thigh which was painless and had no overlying skin changes. X-rays confirmed this finding (Figure 1).
Laboratory Tests
Ultrasound study of the thigh mass revealed a vascular soft tissue mass with some mild heterogeneity (Figures 2a and 2b). No osseous involvement was noted. An MRI of the left femur was obtained to further characterize the lesion, which again demonstrated the mass centered at the left vastus intermedius, concerning for a neoplastic process (Figure 3).
A second soft tissue lesion, questionable for reactive lymphadenopathy vs. metastasis, was identified in the left groin anterior to the common femoral vessels (Figure 4). This was subsequently confirmed as metastatic disease.
FURTHER EVALUATION
The patient was referred to a pediatric orthopedic oncology service for further evaluation. Prior to being seen by this specialist, however, she presented again to the emergency department with complaints of new onset back pain, bilateral lower extremity paraesthesia, and weakness.
Neurological exam revealed decreased strength in the lower extremities bilaterally as well as subjective change in sensation from the level of the umbilicus extending distally. An MRI of the spine was performed which revealed metastatic disease throughout the sacral and lumbar spine, pelvic bones, and the posterior elements of T3-4 and T7. There was also a large posterior epidural mass at T6/T7 dorsal to the cord, causing significant compression (Figures 5a and 5b).
She underwent emergent laminectomy and was subsequently found to have further metastatic disease extending to the calvarium with epidural extension (Figure 6).
What's Your Diagnosis?
A. Neuroblastoma
B. Embryonal rhabomyosarcoma
C. Ewing’s tumors
D. Malignant melanoma
E. Angiosarcoma
(Answer and discussion on next page)
Answer: Embryonal rhabomyosarcoma
Discussion
Thought to arise from primitive mesenchymal cells, pediatric soft tissue tumors may resemble various tissue types—including fibrous, adipose, and muscle. Diagnosis is based primarily on painstaking pathological analysis, although consideration of clinical data (eg, patient age and tumor location) is also imperative. Differentials to be considered include neuroblastoma, Ewing’s tumors, angiosarcoma, synovial sarcoma, malignant melanoma, melanotic neuroectodermal tumors of infancy, granulocytic sarcoma, and malignant lymphoma.1
Prior to 1960, rhabdomyosarcoma was associated with high probability of recurrence and high rates of metastasis. The diagnosis was almost uniformly fatal.2 Since the 1970s, 6 protocols involving over 5000 patients have been done. With respect to extremity rhabdomyosarcomas, the collective recommendations for treatment include initial resection of the localized extremity tumor with sentinel node biopsy, radiation, and systemic chemotherapy (with vincristine, dactinomycin, and cyclophosphamide).3,4 Today, children with the benefit of these multimodal therapies are much more likely to remain free of recurrent and metastatic disease.2
Diagnosis of classic embryonal rhabdomyosarcoma, as seen in this case, has an intermediate prognosis of 66% 5-year survival; botryoid and spindle cell subtypes are associated with superior prognoses, >88% 5-year survival. The alveolar subtype has the poorest prognosis with 54% 5-year survival.
Other important prognostic factors aside from histologic subtype include age at diagnosis and degree of cellular differentiation.1 Tumors located in the bladder, prostate, parameninges, and the extremities are associated with less favorable prognoses. These anatomic sites are of particular prognostic significance because of their association with later detection, larger tumor size, more challenging surgical approaches, and higher likelihood of extension into the meninges and lymphatic system.1
Outcome of the Case
The patient was transferred to a facility with pediatric oncology for further treatment.
Danielle Massarella, MD PGY, is a pediatric resident at MetroHealth Medical Center in Cleveland, OH.
David Effron, MD, is an assistant professor of emergency medicine at Case Western Reserve University, attending physician in the department of emergency medicine at the MetroHealth Medical Center, and consultant emergency physician at the Cleveland Clinic Foundation, all in Cleveland, OH.
References:
- Goldblum JR, Folpe AL, Weiss SW. Rhabdomyosarcoma. In: Goldblum JR, Folpe AL, Weiss SW, eds. Enzinger and Weiss’s Soft Tissue Tumors. 6th ed. Philadelphia, PA: Elsevier; 2014: 601-638.
- Ognjanovic S, Linabery AM, Charbonneau B, Ross JA.Trends in childhood rhabdomyosarcoma incidence and survival in the United States, 1975-2005. Cancer. 2009; 115(18):4218-4226.
- Crist W, Gehan EA, Ragab AH, et al. The Third Intergroup Rhabdomyosarcoma Study. J Clin Oncol. 1995;13(3):610-630.
- Crist W, Garnsey L, Belthangady M, et al. Prognosis in childhood rhabdomyosarcoma: a report of the intergroup rhabdomyosarcoma studies I and II. Intergroup Rhabdomyosarcoma Committee. J Clin Oncol. 1990;8(3):443-452.