Desmin

Characteristics

Desmin is an intermediate filament protein (53 kDa) expressed in all striated muscle cells and most smooth muscle cells. In the developing striated muscle cells it replaces vimentin, linked to the Z-disc (Fig. 1A-B). In the smooth muscle cells desmin is associated with cytoplasmic dense bodies and subplasmalemmal dense plaques. In myofibroblasts and vascular smooth muscle cells desmin is co-expressed with vimentin. However, in the arterial smooth muscle cells, desmin may be scarce or absent (Fig. 1C ), while vimentin expression is retained. Mesothelial cells may express desmin (Fig. 1D), particularly in effusions and cultures.

Desmin play no role in contractility but serves to maintain the orientation of actin and myosin filaments and may also play a role in nuclear transcription.

Neoplasms

Desmin is detected in most tumours of myogenic origin, e.g., leiomyosarcoma (Fig. 2A) and rhabdomyosarcoma. Low differentiated myogenic tumours may lack desmin. Triton tumour, glomus tumour, alveolar soft part sarcoma, and PEComa frequently express desmin. Malignant fibrous histiocytoma, fibrosarcoma, liposarcoma and carcinosarcoma (Fig. 2B) often show focal desmin positivity (as a result of a partial myogenic differentiation). Malignant mesothelioma is positive in about 10% of the cases. A few non-myogenic tumours such as lung adenocarcinoma, malignant melanoma and gliomas are occasionally reported desmin positive. However, in some cases, staining may be due to cross reaction with another intermediate filaments. Gastrointestinal stromal tumour (GIST) is virtually always desmin negative (positivity reported in 5%, possibly in some cases due to staining of entrapped smooth muscle cells).

Application

Desmin is used in a panel for identification of leiomyosarcoma, rhabdomyosarcoma and other tumours with myoid differentiation, and for classification of mesenchymal, pleomorphic, spindle cell and round cell neoplasms.

Visualization

Clone D33 and DE-R-11 are the most commonly used. Heat Induced Epitope Retrieval (HIER) in an alkaline buffer is preferred for both clones.

Assessments

Run 5 2002

Run 21 2007

Selected references

King J, Thatcher N, Pickering C, Hasleton P. Sensitivity and specificity of immunohistochemical antibodies used to distinguish between benign and malignant pleural disease: a systematic review of published reports. Histopathology. 2006 Dec;49(6):561-8. Review.

Miettinen M, Lasota J. Gastrointestinal stromal tumors: review on morphology, molecular pathology, prognosis, and differential diagnosis. Arch Pathol Lab Med. 2006 Oct;130(10):1466-78.

Hornick JL, Fletcher CD. PEComa: what do we know so far? Histopathology. 2006 Jan;48(1):75-82.

Freeman A, Geddes N, Munson P, Joseph J, Ramani P, Sandison A, Fisher C, Parkinson MC. Anaplastic lymphoma kinase (ALK 1) staining and molecular analysis in inflammatory myofibroblastic tumours of the bladder: a preliminary clinicopathological study of nine cases and review of the literature. Mod Pathol. 2004 Jul;17(7):765-71.