This study has validated the recently proposed ISCL/EORTC staging system and identified new prognostic factors.

The clinicopathologic characteristics of 69 cases of eccrine porocarcinoma (EP) have been studied. Seven cases of purely in situ disease are included. Forty patients were female, 29 male with ages ranging from 29 to 91 years (mean 73 years). The lower extremity represented the single most common site (44%). Other common sites were the trunk (15 cases, 24%) and head (11 cases, 18%). The histologic diagnosis of EP was predicated on the basis of an irregular tumor at least partly formed of characteristic poromatous basaloid epithelial cells displaying ductal differentiation, and significant cytologic atypia. Forty-seven tumors (68%) contained mature well-formed eccrine ducts having an eosinophilic luminal cuticle, with the remaining tumors containing small ill-formed ducts and/or intracytoplasmic lumina. All ducts were discernible via light microscopy and in 49 cases were highlighted with DPAS stain and/or CEA/EMA immunocytochemistry. A variant with a broad pushing tumor margin and marked nuclear pleomorphism showed some resemblance to proliferative bowenoid dysplasia. In 11 cases (18%) the tumors appeared to arise in continuity with a benign preexistent poroma. A variety of histologic patterns were displayed including clear, squamous, and spindle cell differentiation, mucus cell metaplasia, and colonization by melanocytes. Lymphovascular invasion was present in 9 cases (15%). Three cases showed pagetoid extension of malignant cells (epidermotropism) and appeared to be multifocal. Follow-up was available in 54 patients (78%) with 9 (17%) experiencing local recurrence, 10 developing lymph node metastases (19%), and 6 (11%) experiencing distant metastases or death. Mitoses, the presence of lymphovascular invasion, and tumor depth >7 mm were associated with a poorer prognosis. Dividing tumors into those with a "pushing" or "infiltrating" advancing margin was also predictive of outcome with the latter having an increased risk of local recurrence. This report, the largest series of EP to date, suggests that the incidence of aggressive behavior is less than popularly believed. Furthermore, EP can display a wide variety of histologic patterns that may lead to diagnostic error in the unwary. The large number of cases in this series enables a reliable evaluation of prognostic parameters. A more aggressive clinical course may be indicated by more than 14 mitoses per high power field (hazard ratio [HR] for death 17.0, 95% confidence interval [CI] 2.71-107), lymphovascular invasion by tumor (HR 4.41, CI 1.13-17.2), and depth >7 mm (HR 5.49, CI 1.0-30.3). Thus, mitoses, lymphovascular invasion, and tumor depth should be evaluated in these tumors. We also suggest that tumors presenting an "infiltrative" advancing margin are particularly prone to local recurrence and require wide excision with close attention to the surgical margins by the reporting pathologist.

Epithelioid hemangioendothelioma of soft tissues (EHE) represents a distinct entity with an unpredictable clinical course. We analyzed the clinicopathologic and immunohistochemical features in a series of 30 patients. Patient age range was 16-74 years (median 50); 18 of 30 patients were female. Eight tumors arose in the lower and two in the upper extremities, seven on the trunk, five each in the head/ neck and anogenital regions, two in the mediastinum, and one in the abdomen. Seventeen neoplasms were located in deep soft tissues, nine were subcutaneous or perifascial, and four were dermal; size ranged from 0.4 to 10 cm; in 11 cases the tumor was > 5 cm. Tumors with an infiltrative growth pattern were more common than entirely circumscribed lesions. The tumors were composed histologically of short strands, cords, or small clusters of epithelioid, round, to slightly spindled endothelial cells that formed at least focally, intracellular lumina and were set in a frequently myxohyaline stroma. Thirteen of 30 lesions showed angiocentric growth, which was occlusive in many cases. Immunohistochemically, all cases tested were positive for at least one endothelial marker (CD31, CD34, factor VIII, Ulex europaeus), six of 23 (26%) were positive for cytokeratin, and five of 11 (45%) were positive for alpha-smooth muscle actin. Median follow-up of 36 months (range 2-96) in 24 cases showed local recurrence in three cases and systemic metastases in five cases (21%); four patients (17%) died of tumor. Although more aggressive histologic features (striking nuclear atypia in eight cases, numerous spindled cells in 10, more than two mitoses per 10 high-power fields in nine, and small, more solid angiosarcomalike foci in four cases) tended to be related to poor clinical outcome, there was no clear correlation. Two metastasizing cases showed no histologically atypical features whatever. We suggest that EHE of soft tissue is better regarded as a fully malignant, rather than borderline, vascular neoplasm, albeit the prognosis is better than in conventional angiosarcoma.