Smooth muscle neoplasms

Smooth Muscle. Smooth muscle neoplasms are combined for all sites of the body, except the gastrointestinal and reproductive tracts, where they are evaluated independently. 

FIGURE 8.7 Smooth muscle neoplasm (A) shows scattered CAMS.2-positive cells (B), a typical focal pattern of immunostaining for keratin seen in a variety of mesenchymal tumors. 

Rizeq MN, van de Rijn M, Hendrickson MR, Rouse RV. A comparative immunohistochemical study of uterine smooth muscle neoplasms with emphasis on the epithelioid variant. Hum Pathol. 1994 25 671-677. 

As in any other organ, immunostains can be of great utility in resolving a variety of spindle cell mesenchymal lesions occurring in the prostate including benign and malignant smooth muscle neoplasms, peripheral nerve sheath tumors, and rhabdomyosarcoma (Table... 

Bell SW, Kempson RL, Hendrickson MR (1994) Problematic uterine smooth muscle neoplasms. A clinicopatho-logic study of 213 cases. Am J Surg Pathol 18 535-558... 

Desmin is a cytoplasmic IFP that is characteristically found in muscle cells and in the neoplasms associated with them. In smooth muscle cells, it is seen with cytoplasmic dense bodies and subplasmalemmal dense plaques in striated muscle, desmin filaments are linked to sarcomeric Z disks. 

S-100 protein reactivity generally should be considered as melanomas. This is especially true if concomitant positivity is obtained for HMB-45, HMB-50, tyrosinase, or MART-1, because the latter four markers are only rarely associated with nerve sheath tumors. Despite the production of collagen type IV by nerve sheath cells, the immunohistochemical detection of this marker has limited value in the diagnosis of schwannian neoplasms because cells with smooth muscle, endothelial, and myo-fibroblastic differentiation may also synthesize it. 

Immunohistochemical studies of these neoplasms have revealed few characteristic features and are used primarily to help exclude other lesions that are under pathologic consideration. Extraskeletal osteosarcomas are reactive for vimentin, and their matrical elements often label for CD57. Alpha-smooth muscle actin may be seen focally, and a subset of tumors is said to coexpress desmin, " perhaps representing myofibroblastic... 

Because muscle-specific actin (recognized by monoclonal antibody HHF-35), alpha-isoform ( smooth muscle ) actin (recognized by antibody 1A4), and caldesmon are also preferentially seen in nonepithelial, nonmelanocytic, nonglial tissues, those determinants would be unexpected in melanocytic neoplasms. Indeed,... 

In the experience of the authors, desmin may be detected as well, although others have disagreed on that point.224 The ultrastructural and biochemical attributes of myofi-broblastic contractile elements are essentially identical to those of smooth muscle cells. Notably, the peculiar intra-cytoplasmic inclusions that are present in DF correspond to aggregates of immunoreactive actin filaments.222-229 Fibrosarcoma of the skin has been reported in association with burn scars, surgical scars, smallpox vaccinations, and other injection sites.221 This exceedingly uncommon neoplasm is composed exclusively of fibroblastic elements and stains only for vimentin, to the exclusion of the other specialized mesenchymal... 

Endometrial stromal neoplasms, both nodules and sarcomas, almost always express CDIO, ER, PR, and WTl (Fig. 18.17).138>141-143,213,214 Many also express P-catenin.2i 2i They frequently express smooth muscle actin,i°°40i,i38,2i4 cytokeratin, 4i4 qj- androgen receptors patchily. They only unusually express des-j inioo,i35,2i9,220 CD34 (unpublished observation) in varieties where the constituent cells resemble non-neoplastic proliferative endometrial stroma. Diffuse desmin and h-caldesmon expression supports smooth muscle differentiation and disqualifies categorization as an endometrial stromal tumor except in rare cases. 

The immunophenotype of this tumor closely parallels that of endometrial stromal neoplasms when stromal overgrowth is not present. The mesenchymal component of miillerian adenosarcomas without stromal overgrowth typically expresses ER, PR, androgen receptors, CD 10, and WTl, while significant minorities also express smooth muscle actin and even pan-cytokeratins (Fig. 18.19).2°F227-229 demonstrating stromal... 

This is a very rare, possibly benign uterine tumor that is characterized by a cytologically bland and largely mitot-ically inactive proliferation of spindle cells in a myxoid matrix. The main differential diagnostic considerations include myxoid leiomyoma and leiomyosarcoma and endometrial stromal neoplasm with myxoid stroma. All inflammatory myofibroblastic tumors reported in the largest series were ALK-positive, which is similar to what has been described to occur in other sites. " All uterine mesenchymal neoplasms studied were ALK-negative, including smooth muscle and endometrial stromal tumors and carcinosarcomas. 

Franquemont DW, Frierson Jr HF, Mills SE. An immunohisto-chemical study of normal endometrial stroma and endometrial stromal neoplasms. Evidence for smooth muscle differentiation. Am J Surg Pathol. 1991 15 861-870. 

Vang R, Kempson RL. Perivascular epithelioid cell tumor ( PEComa ) of the uterus A subset of HMB-45-positive epithelioid mesenchymal neoplasms with an uncertain relationship to pure smooth muscle tumors. Am J Surg Pathol. 2002 26 1-13. 

S-HTj receptors S-HT receptors are important in both brain and peripheral tissues. These receptors mediate synaptic excitation in the CNS and smooth muscle contraction (gut, bronchi, uterus, vessels) or dilation (vessels). The mechanism involves (in different tissues) increased IP3, decreased potassium conductance, and decreased cAMP. This receptor probably mediates some of the vasodilation, diarrhea, and bronchoconstriction that occur as symptoms of carcinoid tumor, a neoplasm that releases serotonin and other substances. 

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