Mojca Velikonja Jože Pižem
An 81-year old woman presented with an exophytic, wart-like skin lesion on her neck that she had observed for one year. Cryotherapy had been applied twice, but proved unsuccessful. At surgical removal, the tumor measured 1.7 cm. It appeared dirty brown and had an ulcerated surface.
Merkel cell carcinoma
CK20
Lymphoma
CD45
Melanoma
S-100
Melan-A
Ewing sarcoma/pnet
CD99
Metastatic neuroendocrine carcinoma
Chromogranin
CD56
Poorly differentiated carcinoma
CK AE1/AE3
CK MNF116
Myogenin
Desmin
MSA
Cutaneous alveolar rhabdomyosarcoma, solid variant
DEFINITION (WHO) A primitive, malignant soft tissue sarcoma that recapitulates the phenotypic and biological features of embryonic skeletal muscles.
CLASSIFICATION Modified conventional (Horn and Enterline) classification used by intergroup rhabdomyosarcoma studies I and II International Society for Pediatric Oncology (SIOP) classification of rhabdomyosarcoma National Cancer Institute (NCI) classification of rhabdomyosarcoma International classification of rhabdomyosarcoma (ICR)
GENERAL FACTS adults < 1% primary cutaneous rhabdomyosarcoma < 1% bimodal age distribution M:F = 1:1
IMMUNOHISTOCHEMISTRY myogenin (Myf-4) desmin muscle-specific actin (HHF35) sarcomeric α-actin myoglobin MyoD1
IMMUNOHISTOCHEMISTRY CD56 panck (CAM 5.2, synaptophysin CK AE1/AE3, MAK6) EMA calponin CD57 NSE vimentin CD99 S-100
ARMS TRANSLOCATION t(2;13), PAX3-FOXO1 ~ 55% t(1;13), PAX7-FOXO1 ~ 20%
ARMS TRANSLOCATION t(2;13), PAX3-FOXO1 ~ 55% t(1;13), PAX7-FOXO1 ~ 20% no translocation ~ 25%
MOLECULAR CLASSES embryonal (ERMS) alveolar fusion gene-negative (narms) alveolar fusion gene-positive (parms)
PROGNOSIS botryoid rhabdomyosarcoma: 95% spindle cell rhabdomyosarcoma: 88% embryonal rhabdomyosarcoma: 66% alveolar rhabdomyosarcoma: 54%
HOW ABOUT OUR PATIENT? diagnosed October 2010 June 2011 metastases: left cervical and supraclavicular lymph nodes July 2011: palliative radiation therapy metastases: lymph nodes (right cervical, upper mediastinum, aortic arch), lungs, soft tissues paravertebrally died August 2011: metastatic disease, acute respiratory distress, acute kidney failure
TAKE HOME MESSAGES 1. Consider a rhabdomyosarcoma in differential diagnosis of cutaneous small round blue cell tumors. 2. Be aware of misleading immunohistochemistry. 3. The most sensitive and specific markers are myogenin and desmin.
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