Myogenin and Myo-D1

Myo-D1, myogenin, MRF4 (also called herculin or myf-6) and myf-5 are members of the Myo-D family of transcription factors and are responsible for initiating striated muscle differentiation. Myf-5 and MRF4 are expressed at specific limited periods in myogenesis. MyoD1 and myogenin are downregulated at birth. MRF4 is the dominant myogenic regulatory factor in adult skeletal muscle.

Antigen retrieval is required. Staining with My-D1 may become weaker if sections are stored for a few days after cutting2. Staining for both antigens is lost with mercury-based fixatives such as B52. Staining is strictly nuclear. Myogenin produces staining that is clearly localised to the nucleus. Myo-D1 is sometimes more difficult to use in paraffin-embedded tissue than is myogenin3. Myo-D1 may show cytoplasmic staining, making the nuclear staining more difficult to discern, but it is the nuclear staining that is significant2. In rhabdomyosarcomas, both antigens may persist within areas of necrosis2.

Immunohistochemical expression

skeletal muscle
lymph nodes may show rare myogenin-positive benign nuclei2.

Myogenin has been detected in:

strongly expressed in alveolar rhabdomyosarcoma and to a lesser extent in other rhabdomyosarcomas.
some cases of fibromatosis1
some cases of infantile myofibromatosis1
some cases of synovial sarcoma1
some cases of leiomyosarcoma1

Myo-D1 is preferentially expressed over myogenin in:

alveolar rhabdomyosarcoma
sclerosing rhabdomyosarcoma

	Myogenin	MyoD1	Desmin
Alveolar rhabdomyosarcoma	97/1002	97/992	positive in 99% of cases2
Embryonal rhabdomyosarcoma	96/992	97/1002
Rhabdomyosarcoma NOS	89/1002	86/1002
Ewings/PNET	0/122	0/122	0/122
Pleuropulmonary blastoma	8/92	8/92	8/92
Haemopoietic	0/52	0/52	0/52
Inflammatory myofibroblastic tumour	0/62	0/62	6/62
Rhabdoid tumour	0/52	0/52	3/52
Synovial sarcoma	0/42	0/42	0/42
Sarcoma NOS	0/42	0/42	0/42
Undifferentiated embryonal sarcoma of liver	0/42	0/42	2/42
Epithelioid sarcoma	0/32	0/32	2/32
Fibrosarcoma	0/22	0/22	1/22
MFH	0/22	0/22	1/22
Angiomatoid fibrous histiocytoma	0/12	0/12	0/12
Angiomyofibroblastoma	0/12	0/12	1/12
Fibrous hamartoma of infancy	0/12	0/12
Mesenchymal hamartoma	0/12	0/12	1/12
Fibromatosis	0/12	0/12	0/12
Epithelioid MPNST	0/12	0/12	0/12
Alveolar soft part sarcoma	0/12	0/12	1/12
Langerhans cell histiocytosis	0/12	0/12	0/12
Germ cell tumour with ERMS	1/12	1/12	1/12
Sertoli-Leydig cell tumour	0/12	0/12	1/12
Osteosarcoma	0/12	0/12	0/12

Both myogenin and Myo-D1 show more intense staining of alveolar rhabdomyosarcoma (ARMS) than they do of embryonal rhabdomyosarcoma (ERMS) or rhabdomyosarcoma NOS2. With myogenin, ARMS shows diffuse staining while ERMS tends to show patchy staining.

Diagnostic utility

Identification of skeletal muscle differentiation. Diagnosis of rhabdomyosarcoma.

References

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 69.

1 Montgomery, E., Goldblum, J.R. and Fisher, C. Leiomyosarcoma of the head and neck: a clinicopathological study. Histopathology 2002;40:518-25.

2 Morotti RA, Nicol KK, Parham DM, et al. An Immunohistochemical Algorithm to Facilitate Diagnosis and Subtyping of Rhabdomyosarcoma: The Children's Oncology Group Experience. Am J Surg Pathol 2006; 30:962-968

3 Stock N, Chibon F, Binh MB, Terrier P, Michels JJ, Valo I, et al. Adult-type rhabdomyosarcoma: analysis of 57 cases with clinicopathologic description, identification of 3 morphologic patterns and prognosis. Am J Surg Pathol. 2009 Dec;33(12):1850-9.

This page last revised 29.3.2010.