CD31 and CD34 expression as immunohistochemical markers of endothelial transdifferentiation in human cutaneous melanoma.

INTRODUCTION: Vasculogenic mimicry, as previously described in aggressive melanoma, is characterized by the de novo generation of intratumoral patterned vascular channels, composed of PAS-positive basement membrane in the absence of endothelial cells, providing additional microcirculation, in support to the classic tumoral angiogenesis. METHODS: We investigated the immunohistochemical expression of two endothelial markers, CD31 and CD34, in tumoral cells of 60 melanomas (45 primary cutaneous and 15 metastatic) as possible evidence of vasculogenic mimicry. In addition we investigated the relationship between CD31 and CD34 expression and three pathological markers such as Clark's level, and skin ulceration, predictive of melanoma's aggressive behaviour, and mitotic index. RESULTS: No cases of common melanocytic nevi immunoreacted with CD31 or CD34. Random CD31 immunoreactivity was present in 6% of Clark's level I/II, 50% of Clark's level III and 80% Clark's level IV/V. CD34 was negative in Clark's level I/II but randomly stained the 20% and 55% of level III and IV/V respectively. 66% (10/15) of metastatic melanomas were CD31 positive showing a canalicular immunostaining pattern, conversely CD34 expression was never found. 7/8 cutaneous ulcerated melanomas immunostained for CD31 and 4/8 for CD34. CD31 immunostained 88% high/intermediate MI, and 53% of low MI melanomas. CD34 decorated the 29% of high/intermediate and 38% of low MI melanomas. CONCLUSIONS: CD31 and CD34 immunoreactivity closely parallel both the different morphologic steps of melanocytic tumor progression and the presence of histological parameters related to the aggressive behaviour. Their expression could be related to endothelial transdifferentiation of melanoma cells although a consequent functional role has not been demonstrated yet.

[Littoral hemangioma of the spleen]. / Emantioma littorale della milza.

The authors report a rare case of littoral hemangioma of the spleen (LHS) accompanied by a revision of the literature on the argument. A male 65-year-old patient was referred to their attention with suspected ultrasonographic diagnosis of lymphoma with a splenic localisation. The complete CT diagnosis led to suspected splenic angioma. During surgery, anatomopathological analysis of the biopsy revealed LHS. The pathological anatomy showed lesions ranging in size from small foci to large nodules which almost completely replaced the splenic parenchyma. These areas were made up of vascular canals or axes that imitate splenic sinuses and have irregular lumen, often appearing as papillary projections and cyst-like spaces; they are bordered by high (cylindrical) endothelial cells that project into the vascular lumen and reveal hemophagocytosis; there is very little mitotic activity. The patient was discharged 7 days after surgery. The authors underline the extreme rarity of this neoplasm and the virtual absence of symptoms, although some cases report signs of hypersplenism, including platelet deficiency and anemia. The diagnostic iter must take care to exclude other pathologies affecting the spleen, including lymphoma, metastases and primary malignant splenic tumours. Lastly, a differential diagnosis must be made with the malignant variant, littoral hemangiosarcoma of the spleen.