Epithelioid cell histiocytoma: A report of 10 cases including a new cellular variant

Cedars-Sinai Medical Center, Los Ángeles, California, United States
American Journal of Surgical Pathology (Impact Factor: 5.15). 07/1994; 18(6):583-90.
Source: PubMed


Epithelioid cell histiocytoma is a recently recognized lesion that is considered to be a variant of cutaneous fibrous histiocytoma (dermatofibroma). Ten cases are presented, including their light microscopic, immunohistochemical, and ultrastructural features. Eight of the cases are similar to those previously reported, presenting as elevated nodules arising on the extremities and composed of epithelioid histiocytes with overlying epidermal effacement. Two of the cases were composed of cells with the same morphologic and immunohistochemical characteristics as typical epithelioid cell histiocytoma, including factor XIIIa positivity, but these arose in the reticular dermis and exhibited prominent cellularity.

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    ABSTRACT: Forty cases of the distinctive but poorly recognized aneurysmal variant of cutaneous fibrous histiocytoma are described. These tumours presented most commonly in middle-age adults, with a slight predilection for females. Anatomical distribution was wide with most cases occurring in the lower limb/limb girdle (50%), upper limb/limb girdle (20%) and trunk (17%). Lesional size ranged from 0.5 cm to 4 cm. Haemorrhage accounted for the rapid clinical growth of some lesions and the frequent clinical confusion with a cyst, a melanocytic lesion or a haemangioma. Five (19%) of the twenty-six cases with follow-up (mean duration 2.5 years) recurred locally, twice in two cases. One of these cases had involvement of a regional lymph node in the second recurrence, most likely as a result of direct local extension. Distinctive histological features were prominent blood-filled spaces, varying from artefact-like clefts to cystic areas mimicking cavernous vascular channels but devoid of an endothelial lining, prominent haemosiderin deposition, numerous siderophages and giant cells, and a moderate mitotic rate. Despite the presence of prominent secondary changes due to haemorrhage, all cases showed cellular polymorphism, hyalinized collagen bundles surrounded by tumour cells in the periphery of the lesion and 88% showed some degree of epidermal hyperplasia, as seen in common fibrous histiocytoma. Immunohistochemistry (ABC method) revealed only vimentin and, rarely, focal smooth muscle actin positivity. CD68 was positive in some reactive macrophages only. Stains for CD31, CD34, desmin and factor XIIIa were negative in all cases tested.(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · May 1995 · Histopathology
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    ABSTRACT: We report on seven examples of this rare, only recently described benign tumor, which presented clinically as solitary elevated nodules on the lower (n=5) and upper (n=2) extremity, measuring between 0.6 and 1.1 cm in diameter. Histologically, all tumors were well-defined with a characteristic epidermal collarette. There were abundant (60–80%) epithelioid cells with prominent cytoplasm, a vesicular nucleus and inconspicuous nucleolus, as well as a number of dilated blood vessels. Immunohistologically, tumor cells did not react with monocyte/macrophage antibodies (KP1, MAC387). In addition, there was no evidence of myofibroblastic differentiation (alpha-smooth muscle actin and desmin negative). Thus, while immunohistological markers are helpful to exclude the diagnosis of other tumors, they do not shed light on the differentiation of epithelioid cell histiocytomas. The present cases are identical to those described originally. Recently similar lesions have been described in deeper parts of the corium as well as more cellular forms. Epithelioid cell histiocytoma represents a characteristic, poorly known variant within the spectrum of benign fibrous histiocytomas; it needs to be distinguished clinically and histopathologically especially from Spitz nevus.
    No preview · Article · Jan 1996 · Der Hautarzt
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    ABSTRACT: Factor XIIIa+ dendrophages and CD34+ "deep dermal dendrocytes" are distinct subsets of embryonic dermal dendritic stem cells that persist in interstitial and adventitial sites in adult dermis. We encountered a unique myxoid dermal tumor composed of these two cell types. It arose after trauma to the thumb of a 49-year-old man and was locally excised. The patient is without recurrence at 18 months. The disc-shaped tumor was lobulated, yellow, and mucoid and involved the margins. A fibrillar myxoid stroma contained mast cells, wispy collagen with medium-to-small vessels, and loosely deployed small eosinophilic tumor cells. The tumor cells were amitotic and had oval or bean-shaped, bland nuclei; some cells were binucleated. The cells were epithelioid or dendritic with bipolar, stellate, and racquet-shaped cytosomes whose tapering cell processes blended with fibrillar collagen. Vacuolated epithelioid cells focally formed vessel-like luminal structure. All cells strongly expressed vimentin. Thirty percent of the tumor cells were elongated, dendritic factor XIIIa+ cells whose dendritic processes enshrouded mast cells or FXIIIa-negative tumor cells. A subset of the FXIIIa+ cells also expressed MAC387 and lysozyme. The other 70% of the cells were CD34+. Many CD34+ cells were epithelioid with strong membrane and vacuolar decoration. Some CD34+ epithelioid cells had globular cytoplasmic inclusions. Other CD34+ cells were dendritic with multipolar fibrobroblast-like cytosomes and weaker CD34+ membrane decoration. Actin and S-100 were negative. Ki 67 was expressed in 1% of the tumor cells. Double stains for CD34 and Ki 67 showed that both CD34+ cells and FXIIIa+ dendrophages were Ki 67+, as were many papillary dermal vessel endothelial cells. The composition of the tumor by mast cells, FXIIIa+ dendrophages, and CD34+ primitive cells recapitulates the dermal microvascular unit. We propose the descriptive term myxoid dermatofibrohistiocytoma (MD) for this novel tumor. It appears to be an unusual response by dermal dendritic cells, perhaps due to continued stimulation by post-traumatic cytokines. Clarification of its biology and nosology awaits identification and study of more cases.
    No preview · Article · Jan 1997 · Journal of Cutaneous Pathology
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