Fibrous papules. A light microscopic and immunohistochemical study

Clinical and histopathological evaluation of cutaneous angiofibromas

BACKGROUND

Angiofibromas are common benign skin lesions that are diagnosed clinically and histopathologically. Fibrous papule (FP) is one of the clinical types of angiofibromas located primarily on the nose.

METHODS

The cases with the confirmed diagnosis of angiofibroma were enrolled. Demographic features of the patients and clinical characteristics of the lesions were extracted. Moreover, histopathological features of the available slides were microscopically reviewed.

RESULTS

From 83 cases of cutaneous angiofibromas, 57 (69%) had lesions consistent with FP. The mean age at diagnosis was 37.7 ± 16.3 years and the most common site of involvement was the nose (53% of cases). Regarding the histopathological evaluation of 71 slides, most cases represented vascular changes (97%) and dermal fibroplasia (87%). Melanin incontinence (41%), acanthosis (31%), and lichenoid features (25%) were other common histopathological findings. Moreover, a sparse inflammatory cell infiltrate was present in 68% of cases. The most prevalent inflammatory cells were lymphocytes (61%) and histiocytes (34%).

CONCLUSION

This study presented the histopathological findings of a series of cutaneous angiofibromas. Dermatopathologists should be aware of these features, especially those that are less common, to better diagnose and differentiate them from malignant neoplasms.

Fibrous papule of the face with granular cells

Fibrous papule of the face is a common benign lesion located most often on the nose. It presents usually as a single small, firm, skin-coloured papule and is often misdiagnosed as melanocytic naevus, wart or small nodular basal cell carcinoma. Histopathologically, the lesions are characterized by involvement of the upper dermis by a fibrovascular proliferation and scattered triangular or stellate, often multinucleated cells. Uncommon histopathologic variants of fibrous papule of the face include hypercellular, clear-cell, pleomorphic, pigmented, inflammatory and granular-cell types. We present here a patient with the syndrome of familial cancer and fibrous papule of the face with granular cells. The granules stained strongly with PAS stain, as well as with CD68 and NKI/C3 immunostains, whereas S-100 protein resulted negative. In our patient the mutations in the 2 most often affected DNA mismatch repair genes of Muir-Torre syndrome were not found, therefore the origin of the familial cancer syndrome remains unknown. Probably the occurrence of the granular-cell fibrous papule of the face was coincidental.

Histologic variants of fibrous papule

Fibrous papules (FPs) are common benign lesions usually of the face. Most are readily recognizable histologically, although several variants exist that may not be as easily diagnosed. These include hypercellular, clear cell, pigmented, pleomorphic, and inflammatory variants. A granular cell variant has also been described. We microscopically evaluated 212 FPs, and of those, 184 demonstrated features of one of the variants. We conclude that variants of FP may be encountered not uncommonly. Dermatopathologists should be aware of these to avoid misdiagnosis.

Immunohistochemical investigation of the different developmental stages of trichofolliculoma with special reference to the Merkel cell

The morphologic features of trichofolliculoma are variable, reminiscent of the anagen, catagen, and telogen phases of a normal hair follicle in its cycle. We recently described an early, fully developed stage and late stages of trichofolliculoma. Using immunohistochemical examination, we sought to demonstrate hyperplasia of Merkel cells in all three stages of trichofolliculoma. We found this to be the most striking in small lesions of the late stage. The distribution of the Merkel cells in several stages of trichofolliculoma coincided with the known arrangement of normal follicular Merkel cells during the follicular cycle. However, antibodies against neurofilaments failed to detect innervated Merkel cells, in contrast to normal follicular Merkel cells. Antibodies against Ki67 did not reveal proliferative Merkel cells in any of the trichofolliculomas, but for unknown reasons, a distinct cytoplasmic staining of Merkel cell processes sometimes occurred. Nuclear Ki67 was strongly expressed in the nuclei of follicular keratinocytes of the fully developed trichofollicullomas, whereas those at a late stage showed a markedly decreased staining pattern. Our finding of Merkel cells in all trichofolliculomas underlines their classification as hamartomas with follicular differentiation. Hyperplasia of Merkel cells, even in trichofolliculomas at a late stage, as regressing lesions might implicate hitherto unknown regulatory functions of this neuroendocrine cell.

Cutaneous vascular proliferations. Part III. Malignant neoplasms, other cutaneous neoplasms with significant vascular component, and disorders erroneously considered as vascular neoplasms

In this third and last part of our review of cutaneous vascular proliferations we include malignant vascular neoplasms and a group of heterogeneous cutaneous neoplasms characterized by a significant vascular component. We also review some disorders that, in our opinion, have been erroneously considered as vascular neoplasms. We review the epidemiologic, histogenetic, clinical, and histopathologic aspects of Kaposi's sarcoma in its four distinctive variants (classic, African-endemic, immunosuppressive drug-associated, and AIDS-associated Kaposi's sarcoma). There is still controversy about whether Kaposi's sarcoma represents a reactive vascular proliferation or a true neoplastic proliferation. In any event, most authors believe that Kaposi's sarcoma does not produce metastatic disease, but rather develops in multifocal fashion. However, Kaposi's sarcoma may cause death, especially in immunosuppressed patients. Epithelioid hemangioendothelioma, Dabska's tumor, and retiform hemangioendothelioma are examples of low-grade angiosarcoma. In contrast, cutaneous angiosarcomas, including the clinical variants of angiosarcoma of face and scalp in elderly patients, angiosarcoma associated with lymphedema, and radiation-induced angiosarcoma are highly aggressive neoplasms with poor prognosis and most patients die within a short period after presentation. A group of benign and relatively frequent cutaneous neoplasms, including multinucleate cell angiohistiocytoma, angiofibroma, angioleiomyoma, angiolipoma, cutaneous angiolipoleiomyoma, and cutaneous angiomyxoma are here covered because of their significant vascular component. Finally, we review briefly a series of cutaneous disorders that have been erroneously considered as vascular neoplasms. Kimura's disease is an inflammatory reactive condition of unknown origin, "benign" angioendotheliomatosis is a reactive intravascular proliferation of endothelial cells that occurs in the skin as a response to a variety of stimuli, "malignant" angioendotheliomatosis is an intravascular lymphoma, and acral pseudolymphomatous angiokeratoma of children (APACHE) is better interpreted as a pseudolymphoma.

Fibrous papule of the nose with granular cells: two cases

Two cases of fibrous papule of the nose (FPN) with granular cell features are presented and discussed. Both lesions have classic architectural features of FPN; however, the main stromal cells show large cytoplasmic granules of the type seen in granular cells. We are uncertain of the significance of these findings. Our hypotheses include a perifollicular granular cell reaction and a granular degenerative change of local dermal dendrocytes.

Neurofollicular hamartoma: a light microscopic and immunohistochemical study

Neurofollicular hamartoma is an unusual, previously undescribed neoplasm characterized by a proliferation of spindle cells and hyperplastic pilosebaceous units. Five cases were reviewed. The lesions presented as single, asymptomatic, smooth, flesh-colored papules. Four were on the nose, and one on the adjacent nasolabial fold. Immunoperoxidase studies performed on two cases utilizing antibodies to S-100 antigen were positive in both. These lesions share some histological and clinical features with angiofibroma and neurofibroma.

An immunohistochemical study of fibrous papule of the nose: 25 cases

Twenty-five cases of fibrous papule of the nose were studied by light microscopy and by immunohistochemistry using a panel of 4 cell markers. These included polyclonal antibodies against S100 protein and Factor XIII-a (FXIII-a), and 2 monoclonal antibodies, MAC 387 which labels monocyte derived macrophage cells and Ulex Europaeus Agglutinin-1 (UEA-1) a pan endothelial cell marker. An increase in the number of S100 protein positive cells, particularly in the upper dermis, was observed in 3 lesions. Melanin was identified in phagocytes in the superficial dermis in 6 lesions, including those with S100 protein positive cells. In all of the papules there was a marked increase in FXIII-a labelling of dendritic connective tissue cells, including spindle, stellate and multinucleate stellate cells. Immunoreactivity with FXIII-a was especially strong in the increased mononuclear dendritic cell population (greater than 80%) seen in the mid- and upper dermis. However, only 15% of the larger multinucleate stellate cells were immunostained with FXIII-a. The results achieved with markers to the macrophage cell series (MAC 387) or endothelial cells (UEA-1) showed no significant increase in labelling of the dermal cell population compared to normal skin taken from the nose. Our study suggests that fibrous papule of the nose, a lesion of uncertain histogenesis, probably represents a proliferative reactive process consisting mainly of dermal dendritic cells as identified by FXIII-a in most of the lesions. There is some evidence that a small percentage of the dendritic cells may represent involuted naevi and be of melanocytic origin.