Dermatofibroma with osteoclast-like giant cells.

Dermatofibroma (DF), or cutaneous fibrous histiocytoma, is a common cutaneous tumor with many variants that may arise from alterations in the morphology and composition of its various components. One type that has not received much attention is DF with osteoclast-like giant cells. Two cases of this rare tumor are described. The importance of this tumor lies in the possible histologic confusion with a variety of benign and malignant neoplasms, including giant cell tumor of tendon sheath, giant cell tumor of bone, and giant cell reparative granuloma.     

Atypical fibroxanthoma: two unusual variants

Two unusual fibroxanthomas were studied by light microscopy. The first case contained numerous osteoclast-like cells and resembled malignant giant cell tumour of soft tissues, a variant of malignant fibrous histiocytoma. Osteoclast-like giant cells were negative for lysozyme and alpha-1-antitrypsin. The second case contained areas of chondroid differentiation which resembled chondrosarcoma. Tumour cells within the cartilaginous areas were positive for S100 protein.     

Ulcerated dermatofibroma with osteoclast-like giant cells

Background: Ulceration and osteoclast-like giant cells are two pathological features uncommonly seen in dermatofibromas. To our knowledge, the presence of these features has not been previously described within the same lesion.
Methods: We report the clinical, histopathological and immunohistochemical findings of a 38-year-old man with an ulcerated dermatofibroma (DF) on the sole containing OLGC.
Comments: DF, or cutaneous fibrous histiocytoma, is a frequent dermatological lesion with many clinicopathological variants. Therefore, a correct diagnosis is not always straightforward, especially when two rare features co-exist in the same lesion. Differential diagnosis was performed with cutaneous and even non-cutaneous lesions. An explanation for the clinicopathological findings is also described.     

Benign fibrous histiocytoma of the eyelid with an unusual clinical presentation

Benign fibrous histiocytoma is a common soft tissue tumor that can be deep or superficially located. Although the deep type of fibrous histiocytoma has a predilection for the orbit, the eyelids are an unusual location for the cutaneous type. A 42-year-old woman had bilateral yellowish nodular masses of the eyelids for two years. Pathological examination after excision revealed benign fibrous histiocytoma. Our case is an unusual clinical presentation of cutaneous fibrous histiocytoma as well as a rare location such as the eyelids.     

The value of immunohistochemistry in atypical cutaneous fibrous histiocytoma

Atypical cutaneous fibrous histiocytoma is a rare variant of dermatofibroma/fibrous histiocytoma characterized by striking atypia, thus resembling atypical fibroxanthoma. We studied 9 examples of ACFH histopathologically and immunohistochemically to investigate the nature of these atypical cells. Histology revealed ill-defined skin nodules, which were polypoid in 6 cases. A minority of mononuclear and giant cells (< 5%) revealed striking pleomorphism and showed large nuclei with prominent nucleoli. Immunohistologically, the atypical cells expressed vimentin, but were negative for S-100 protein, the keratin marker MNF116, alpha smooth muscle actin, CD34, factor XIIIa, and monocyte/macrophage markers Ki-M1p, KP1 (CD68), and MAC387. Positivity for MiB1 was very modest (< 1%) and limited to small- and medium-sized, inconspicuous cells. Multinucleate giant cells proved to be heterogenous, on one hand cells with differentiation toward macrophages with positivity for Ki-M1p and KP1, on the other toward fibroblasts positive for vimentin only. These immuno-histochemical results for differentiation markers in atypical cutaneous fibrous histiocytoma are similar to our previous findings and data in atypical fibroxanthoma; MiB1 helps to separate these entities from each other as the latter shows a very high proportion of proliferative atypical cells corresponding to the numerous mitoses seen in routine sections.     

Fibrohistiocytic skin tumors

The fibrohistiocytic tumors of the skin are a heterogeneous group of dermal/subcutaneous mesenchymal neoplasms which show fibroblastic, myofibroblastic and histiocytic (macrophage‐like) differentiation, often one beside the other in the same tumor. “Fibrohistiocytic” means in this context the morphologic similarity of the cells with fibroblasts and histiocytes. The WHO classification of 2005 includes the following entities as fibrohistiocytic tumors of the skin: Benign: 1. Fibrous histiocytoma (FH)/(synonymous: Dermatofibroma. Variants of FH: 1a. cellular fibrous histiocytoma, 1b. atypical (pseudosarcomatous) fibrous histiocytoma, 1c. aneurysmatic fibrous histiocytoma, 1d. epithelioid fibrous histiocytoma; 2. dermatomyofibroma; 3. (juvenile) xanthogranuloma. Intermediate: 4. plexiform fibrohistiocytic tumor; 5. dermatofibrosarcoma protuberans; 6. atypical Fibroxanthoma. Malignant: 7. malignant fibrous histiocytoma. All these entities are reviewed in this paper with particular attention devoted to differential diagnostic considerations.     

Primary giant cell tumor of soft tissue

BACKGROUND: Primary giant cell tumor of soft tissue, also known as soft tissue giant cell tumor of low malignant potential, is a rare soft tissue tumor located in both superficial and deep soft tissue. Histologically, these lesions bear a close resemblance to their bony counterparts, giant cell tumor of bone, with round to spindle-shaped cells intimately admixed with uniformly scattered osteoclast-like multinucleated giant cells. In 1989 in the dermatology literature, two malignant giant cell tumors of soft parts were described that filled the dermis and extended into the subcutaneous tissue. METHODS: The authors report the rare occurrence of a giant cell tumor of soft tissue occurring primarily in the dermis that lacks overtly malignant features and clinically was thought to be an epidermal inclusion cyst. RESULTS: Light microscopy revealed a non-encapsulated cellular dermal tumor containing numerous osteoclast-like giant cells. Cytologic atypia was minimal and the mitotic count averaged 2-3/10 HPF. The histologic differential diagnosis is also discussed. CONCLUSION: Giant cell tumor of soft tissue is a rare neoplasm of the skin, however, recognition of this tumor is important due to its behavior as a low-grade malignancy.     

Benign fibrous histiocytoma of the foot: a literature review and case report

A rare case of benign fibrous histiocytoma involving the foot of a sixty-three-year-old white man is presented, with a review of the literature. The histopathologic appearance of benign fibrous histiocytoma, differential diagnosis, and surgical management are discussed. Fibrous histiocytomas are characteristically nonencapsulated tumors composed of a mixture of fibroblastic and histiocytic cells arranged in a storiform or cartwheel pattern.     

Plexiform fibrohistiocytic tumor without multinucleated giant cells: a case report

Plexiform fibrohistiocytic tumor (PFT) is a rare but distinctive soft tissue tumor of children and young adults characterized by a mixture of histiocyte-, myofibroblast-, and osteoclast-like giant cells arranged in a plexiform pattern. We report the clinicopathologic and immunohistochemical features of an apparently unique case of PFT without multinucleated giant cells presenting in a 3-year-old child. Light microscopy revealed a subcutaneous tumor composed of a plexiform proliferation of histiocyte- and myofibroblast-like cells. Multinucleated osteoclast-like giant cells, the third classic cellular component of this mesenchymal neoplasm, were not observed. The differential diagnosis is also discussed. Emphasis is placed on the importance of the recognition of PFT, because it may exhibit an aggressive behavior.     

Cutaneous and subcutaneous fibrohistiocytic tumors of intermediate malignancy: an update

The fibrohistiocytic tumors of intermediate malignancy are uncommon mesenchymal tumors, which typically occur in the skin and subcutis and which may pose significant problems for the dermatopathologist. This article reviews the clinical, histopathologic, and genetic features of dermatofibrosarcoma protuberans, giant cell fibroblastoma, angiomatoid (malignant) fibrous histiocytoma, plexiform fibrous histiocytoma, and soft tissue giant cell tumor (of low malignant potential). The differential diagnosis of these tumors with a variety of benign and fully malignant cutaneous soft tissue neoplasms is discussed.     

Giant cell tumor of skin

Giant cell tumor of the skin is a rare entity showing gross and histological features similar to those of giant cell tumor of the bone. We report a case of malignant giant cell tumor of the thigh in a 55-year-old man. Histological features showed a biphasic population of mononuclear cells admixed with osteoclast-like giant cells. The nuclei of the giant cells were similar to those of the mononuclear cells. This tumor should be distinguished from a variety of cutaneous neoplasms that contain multinucleated giant cells.     

Primary giant cell tumor of soft tissue of the groin – a case of 46 years duration

Background: Soft tissue giant cell tumor (GCT-ST) of low malignant potential is an uncommon neoplasm, considered the soft tissue counterpart of giant cell tumor of bone. GCT-ST mainly affects young to middle-age adults and presents as a painless growing mass mainly located in the lower extremities and trunk. Histologically, this tumor is characterized by a mixture of uniformly scattered osteoclast-like multinucleated giant cells intimately admixed with short fascicles of spindled cells. Complete excision with negative surgical margins is associated with a benign clinical course in most cases.
Methods: The authors report the clinicopathological and immunohistochemical features of an unusual GCT-ST of 46 years duration previously histologically misdiagnosed as Kaposi's sarcoma.
Results: Histologically, the tumor was characterized by a multinodular growth pattern with osteoclast-like multinucleated giant cells admixed with spindle cells partially arranged in a storiform pattern, fibrosis and foci of haemorrhage and mature bone. Immunohistochemistry revealed CD68 reactivity of the multinucleated giant cells.
Conclusion: GCT-ST is a rare neoplasm characterized by benign clinical course if excised adequately, as shown by our case of exceptionally long duration. Emphasis is placed on the importance of differential diagnosis with other giant cell-rich soft tissue neoplasms because clinical behaviour, prognosis and treatment significantly differ.     

Malignant fibrous histiocytoma arising from chronic ulcer

A patient had malignant fibrous histiocytoma that developed in a chronic ulcer. Squamous cell carcinoma can develop on long-standing ulcers, but malignant fibrous histiocytoma developing in an ulcer is extremely rare.     

硬皮病样皮肤转移性恶性纤维组织细胞瘤1例

报告1例硬皮病样皮肤转移性恶性纤维组织细胞瘤。患者男,60岁。面颊及颈部皮肤硬韧1个半月。病理检查示:真皮浅中层胶原纤维间见散在或密集的类似成纤维细胞样细胞、组织细胞样细胞浸润,细胞核大而深染,呈长梭形及圆形,小血管腔内也见核大深染的细胞及多核巨细胞。免疫组化示:CD68(+),CD34,CK,SMA均阴性。诊断:皮肤转移性恶性纤维组织细胞瘤。     

Aneurysmal Benign Fibrous Histiocytoma with Atrophic Features

Aneurysmal benign fibrous histiocytoma is an uncommon pathologic variant of dermatofibroma. In addition to the features of a typical dermatofibroma, it has large cleft-like or cavernous blood-filled spaces with numerous hemosiderin pigments. It should be differentiated from angiomatoid malignant fibrous histiocytoma, malignant melanoma, and vascular tumors such as Kaposi''s sarcoma and angiosarcoma. Atrophic dermatofibroma is also a rare variant of dermatofibroma, and the combination of aneurysmal and atrophic features is rarer still. We report a case of aneurysmal benign fibrous histiocytoma with atrophic features in a 27-year-old male who had a grayish-brown atrophic patchy lesion on his back for 2 years.     

Atypical cutaneous fibrous histiocytoma

We report seven cases of atypical cutaneous fibrous histiocytoma, which appears to be a variant of cutaneous fibrous histiocytoma (dermatofibroma). These patients are all middle-aged women (mean, 39 years old) with small nodules occurring on the trunk and limbs. The lesions are characterized by marked focal cellular atypia, the absence of mitoses, and xanthomatous changes in both mononuclear and giant cells--all found within a small dermal nodule (approximately 1 cm) separated from an acanthotic epidermis by a Grenz zone. Their benign nature is demonstrated by the absence of recurrence, even after 9 years follow-up time.     

Malignant giant cell tumor of soft parts presenting as a skin tumor

Malignant giant cell tumor of soft parts is a rare neoplasm that histologically resembles a giant cell tumor of bone. It has a distinctive multinodular growth pattern and is composed of numerous osteoclast-like giant cells, histiocytes, and fibroblasts. Although this tumor is usually found in deep soft tissues, a superficial form has been described in the subcutaneous tissue and fascia. The authors report two patients, aged 75 and 78, with malignant giant cell tumors presenting as ulcerating skin nodules of the arm and foot. The tumors were relatively small, measuring less than 3.5 cm in greatest dimension, and involved the entire dermis and subcutaneous tissue. The clinical differential diagnoses included Kaposi's sarcoma, melanoma, and hematoma. Dermatopathologists and dermatologists should be aware of this entity to avoid confusion with other benign and malignant neoplasms that may contain multinucleated giant cells. The distinguishing histologic and immunohistochemical features of this tumor are discussed.     

Poorly differentiated squamous cell carcinoma with osteoclastic giant-cell-like proliferation

Although osteoclast giant-cell-like proliferations have been reported in a diverse range of human malignancies, to the best of our knowledge, they have never been described in cutaneous squamous cell carcinoma (SCC). Histologically, osteoclastic giant cell tumors within extraosseous malignancy resemble their bony and soft tissue counterparts, with round to spindle-shaped cells admixed with osteoclast-like multinucleate cells. These cells should be distinguished from sarcomatoid differentiation within a carcinoma; they have a benign morphology with a low nuclear to cytoplasmic ratio, minimal pleomorphism/mitoses and negative immunohistochemistry for cytokeratin. The authors report the rare occurrence of osteoclast-like giant cells (OGCs) and accompanying epithelioid histiocytes lacking overtly malignant features in association with a poorly differentiated SCC occurring on sun-damaged skin. Immunohistochemically, the area rich in OGCs was strongly positive for CD68 and completely negative for cytokeratin, whereas the poorly differentiated infiltrative area had the reverse immunophenotype and nuclear positivity for p63. The histological differential diagnosis and the origin of the proliferation are discussed in this article.     

Case for diagnosis

Atypical fibroxanthoma is a rare cutaneous tumor found mainly in elderly people on sun-exposed areas of the body. Histologically, atypical fibroxanthoma is considered a malignant fibrous histiocytoma with bizarre neoplastic cells, marked pleomorphism, hyperchromatic nuclei and abundant mitoses. It must be differentiated from other skin tumors, usually by immunohistochemistry, since its diagnosis is made by exclusion.