h-Caldesmon

Immunohistochemical expression

Caldesmon, originally purified from gizzard smooth muscle⁶, is a cytoskeleton-associated protein present in smooth and non-smooth muscle cells. Binding to actin, tropomyosin, calmodulin, myosin and phospholipids, it counteracts actin-tropomyosin activated myosin-adenosine triphosphatase, thereby inhibiting calcium-dependent contraction of smooth muscle⁵. It exists in low and high molecular weight forms. The low molecular weight form (l-Caldesmon) is present in many cell types. The high molecular weight isoforms (89 to 93 kD) are thought to be restricted to visceral and vascular smooth muscle and myoepithelial cells. (Myoepithelial cells show variable staining while the limited number of tumours of myoepithelial cells studied by Watanabe were all negative².) Anti-h-caldesmon appears to be a more specific identifier of smooth muscle differentiation than are desmin, muscle specific actin and alpha smooth muscle actin. A commercially available monoclonal antibody (h-CD) works on paraffin sections.

	h-caldesmon	desmin (D33)	muscle specific actin (HHF-35)	smooth muscle actin
Myometrium	40/404	40/404
Leiomyoma	6/62, 10/104	6/62, 10/104	6/62	6/62
Uterine cellular leiomyoma	8/113, 14/144	10/113, 14/144		10/113
Uterine highly cellular leiomyoma	8/84	8/84
Angioleiomyoma	2/22	2/22	2/22	2/22
Leiomyosarcoma	19/261,2,3, 29/294	24/261,2,3, 28/294	17/171,2,3	26/261,2,3
Gastric stromal tumour	2/82	0/82	6/82	1/82
Glomus tumour	3/32	0/32	3/32	3/32
Rhabdomyosarcoma	0/82	8/82	8/82	2/82
MFH	0/341,2	5/341,2	11/341,2	11/341,2
Synovial sarcoma	0/41	0/41	0/41	0/41
MPNST	0/51	0/51	0/51	2/51
Endometrium	0/254	8/254
Endometrial stromal neoplasm	0/123, 0/244	1/123, 12/244		1/123
Fibromatosis	0/151,2	10/151,2	13/151,2	14/151,2
Nodular fasciitis	0/41	0/41	2/41	4/41
Cellular cutaneous fibrous histiocytoma	0/111	3/111	1/111	6/111
Salivary pleomorphic adenoma	0/22	0/22	1/22	1/22
Salivary myoepithelioma	0/12	0/12	1/12	1/12
Salivary epithelial-myoepithelial carcinoma	0/12	0/12	1/12	1/12
Chondroid syringoma	0/22	0/22	2/22	0/22
Desmoplastic stroma	0/51	0/51	4/51	5/51
Inflammatory pseudotumour	0/22	1/22	2/22	2/22
Myofibroblastic reaction	0/51	0/51	4/51	5/51

Fibrous capsule of thyroid lesions: h-caldesmon-positive spindle cells are present in the fibrous capsule of hyperplastic nodules and follicular neoplasms, but not encapsulated papillary carcinomas.

	h-caldesmon positive spindle cells
hyperplastic nodule	20/216
follicular adenoma	29/296
minimally invasive follicular carcinoma	5/56
widely invasive follicular carcinoma	4/66
encapsulated papillary carcinoma	0/96

Diagnostic utility

• The differentiation of true smooth muscle tumours from myofibroblastic tumours.

• In combination with CD10, the differentiation of endometrial stromal sarcoma from uterine smooth muscle tumours⁴. Highly cellular leiomyomas in particular mimic endometrial stromal neoplasms.

References

¹KM Ceballos et at. Is anti-h-caldesmon useful for distinguishing smooth muscle and myofibroblastic tumors? Am J Clin Pathol 2000;114:746-753.

²K Watanabe et al. h-Caldesmon in leiomyosarcoma and tumors with smooth muscle cell-like differentiation: its specific expression in the smooth muscle cell. Hum Pathol 2000;30:392-396.

³DS Rush et al. h-Caldesmon, a novel smooth muscle-specific antibody, distinguishes between cellular leiomyoma and endometrial stromal sarcoma. Am J Surg Pathol 2001;25:253-258.

⁴MR Nucci et al. h-Caldesmon expression effectively distinguishes endometrial stromal tumors from uterine smooth muscle tumors. J Pathol 2001;25:455-463.

⁵Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 70.

⁶Nakayama, H., Enzan, H., Miyazaki, E., Moriki, T., Kiyoku, H., Toi, M., Kuroda, N. and Hiroi, M. High molecular weight caldesmon positive stromal cells in the capsule of thyroid follicular tumours and tumour-like lesions. J Clin Pathol 2002;55:917-20.

This page last revised 13.5.2003.

©SMUHT/PW Bishop