|
| Tumor | Age of presentation | Most frequent location | Form of the lesion | Histology | Cytology | Immunohistochemistry | Molecular alteration |
|
| For CM with sheets of epithelioid, ovoid, or histiocytoid cells and solid growth pattern |
| Benign epithelioid fibrous Histiocytoma | Adults, second to fifth decades | Lower limbs and trunk | Exophytic, polypoid | Highly vascularized stroma with scattered inflammatory cells. Trapping of collagen bundles at the periphery of the lesion. | Epithelioid cells, often binucleated | S-100 (-), keratin (-), EMA (+/-), SMA (-/+), calponin (-) | AKL gene rearrangement. Identified fusion genes include SQSTM1, VCL, DCTN1, ETV6, PPFIBP1 and SPECC1L |
| Spitz nevus | Frequent in children; 65% of all cases occur in adolescents and young adults | Head and neck, trunk and lower limbs | Semispherical nodule | Solid pattern with cellular nests. Kamino bodies. | Epithelioid melanocytes with prominent nucleoli | S-100 (+), HMB45 (+), Melan-A (+), keratin (-), EMA (-), GFAP (-) | Alteration of the HRAS gene has been reported |
| Epithelioid sarcoma | Young adults | Distal portion of the extremities | Exophytic | Multinodular, very evident and diffuse infiltration with no myxoid or hyalinized stroma | Epithelioid to fusiform | Keratin (+), EMA (+), S-100 (-), GFAP (-) | Deletions of SMARCB1; gain of chromosomes 11, 1, 6, and 9 have been reported |
|
| For CM composed predominantly of spindle cells |
| Pilar leiomyoma | Young adults; may be congenital | Limbs and trunk | Nodule (usually painful) | Cellular bundles ramifying between collagen fiber bundles | Fusiform | Desmin (+), S-100 (-), GFAP (-), keratin (+/-), EMA (+/-) | Not reported |
|
| For CM showing reticular pattern and myxoid matrix |
| Ossifying fibromyxoid tumor | Adults, fifth decade of life | Lower and upper limbs | Exophytic | Lobular o multinodular | Round or ovoid | S-100 (+), desmin (+), keratins (+/-), GFAP (+/-) | PHF1 gene rearrangement |
| Extraskeletal myxoid chondrosarcoma | Adults, peak in the sixth decade | Limbs, especially the groin and gluteal region | Exophytic | Lobular or multinodular; reticular or trabecular pattern. Greater cellularity towards the periphery of the nodules. | Fusiform to epithelioid | Keratins (-), p63 (-), GFAP (-), SMA (-), EMA (-/+), S-100 (-/+) | Translocation t (9; 22) (q22; q12)–NR4A3-EWSR1. |
|
