Seborrheic keratoses and trichostasis spinulosa

Squamous Eddies in Irritated Seborrheic Keratosis

Seborrheic keratosis is related to the intraepidermal hair follicle in its morphogenesis. Squamous eddies in irritated seborrheic keratosis (ISK) are known to develop by focal maturation of basaloid cells, but the significance of squamous eddies is not understood. The purpose of this study was to elucidate the nature of squamous eddies in ISK. Serial sections of paraffin blocks of 20 cases of ISK were examined. We tracked each squamous eddy through the serial sections to observe the different shapes and positions of the same squamous eddy. In 4 cases, squamous eddies revealed hair shafts at their centers in different sections. In 14 cases, squamous eddies contained acrotrichial canals. In 13 cases, squamous eddies were connected to keratotic invaginations we thought to be follicular infundibula. Eighteen of the 20 cases of ISK showed at least 1 of the morphological features of intraepidermal hair follicle structures. We have found that the squamous eddies of ISK are anatomically related to acrotrichia.

Seborrheic keratosis with pseudorosettes and adamantinoid seborrheic keratosis: two new histopathologic variants

AIMS

Seborrheic keratoses are the most common benign cutaneous neoplasms in adult and middle-age patients. There are six distinctive histopathologic variants of seborrheic keratosis, namely, acanthotic or solid, reticulated or adenoid, hyperkeratotic or papillomatous, clonal or nested, irritated and inflamed.

METHODS

We report two additional histopathologic variants of seborrheic keratosis.

RESULTS

One lesion showed abundant intercellular mucin, closely resembling to adamantinoma, and therefore was named adamantinoid seborrheic keratosis. The other one exhibited a peculiar distribution of the basaloid keratinocytes, which were arranged radially around small central spaces, resulting in pseudorosette formation.

DISCUSSION

To our knowledge, these two histopathologic variants of seborrheic keratosis have been not previously described in the literature.

Trichostasis spinulosa arising within syringoma

A forty-eight-year-old man presented with multiple pinhead to rice-sized papules on the face. Histopathologic examination showed a typical syringoma and dilated hair follicles containing several vellus hairs in the middle of a fibrotic stroma. We discuss the possible pathomechanism between these two conditions in the same lesion.

Melanocytic matricoma: case confirmation of a recently described entity

BACKGROUND

In 1999, Carlson et al. reported two cases of a matrical neoplasm that recapitulates the bulb of the anagen hair follicle, which they designated as melanocytic matricoma.

METHODS

Here we report a similar case in a 78-year-old white male, who presented with a 0.4 cm purple-black firm papule in the left preauricular area.

RESULTS

Histologically, the tumor is composed of a dual cell population including admixed epithelial matrical and supramatrical cells with "shadow" cell formation and pigmented dendritic melanocytes. Immunohistochemical studies for cytokeratin highlighted the epithelial component and studies for S-100 protein, HMB-45, and vimentin confirmed the melanocytic component. The differential diagnosis considered includes pigmented variants of pilomatricoma, matrical carcinoma, basal cell carcinoma and malignant melanoma.

CONCLUSIONS

The case reported herein is the first confirmation of melanocytic matricoma, a distinctive adnexal neoplasm with characteristic clinical and pathologic features, which differentiate it from pigmented pilomatricoma.

Follicular basal cell hyperplasia overlying dermatofibroma

Follicular basal cell hyperplasia (FBCH) overlying dermatofibroma represents aborted or impeded pilar differentiation. Historically, this hyperplasia has been misinterpreted as basal cell carcinoma. In a large series of dermatofibroma (258 cases), those that contained primitive or malformed follicular structures over the lesion (59 cases) were compared with those without such elements (199 cases). Statistical analysis of various clinicopathologic features showed that FBCH was significantly associated with younger age, trunk location, hypercellular dermatofibroma, loss of a Grenz zone, clear cell hyperplasia, and seborrheic keratosis-like change. There was an inverse correlation between epidermal atrophy, lichen simplex chronicus-like change, and lower extremity location with FBCH. Histologic features favoring a diagnosis of FBCH over basal cell carcinoma are the focal nature and superficial location of the lesion, lack of cytologic atypia and mitoses, recognizable components of hair follicle differentiation, focal condensation of mesenchymal cells around basal cell proliferation, and the association of epidermal hyperplasia. Our findings suggest that FBCH, clear cell hyperplasia, and seborrheic keratosis-like change all represent an expression of follicular differentiation overlying dermatofibroma.

The relationship between basal cell epithelioma and seborrheic keratosis. A study of 60 cases

BACKGROUND

Various skin tumors can be seen rarely in association with seborrheic keratosis. We present 60 cases of seborrheic keratosis related to a basal cell epithelioma in the same specimen.

OBJECTIVE

To report association of basal cell epithelioma with seborrheic keratosis and discuss the possibility of malignant change in seborrheic keratosis.

METHODS

Sixty cases of seborrheic keratosis associated with basal cell epithelioma were studied. Tissues were fixed in neutral buffered formalin, processed, and stained with standard hematoxylin and eosin techniques.

RESULTS

Histological evaluation showed a seborrheic keratosis associated with basal cell epithelioma in all of the cases. Basal cell epithelioma was attached with seborrheic keratosis in a majority of the cases (40/60) and appeared to represent a part of the same tumor. Both tumors were lying adjacent to each other in the rest of the cases (20/60).

CONCLUSION

Malignant change in seborrheic keratosis is controversial. We recommend the histological evaluation of seborrheic keratosis especially when inflamed or atypical in appearance. This should not be taken as a mandate for pathological evaluation or for treatment of every seborrheic keratosis as though it was potentially malignant.

Detection of human papillomavirus DNA in seborrheic keratosis by polymerase chain reaction

We searched for HPV DNA in 72 cases of seborrheic keratosis (nongenital SK 29, genital SK 43) using polymerase chain reaction. Amplification of HPV DNA was found in 24 (nongenital, 1; genital, 23). HPV DNA type 6 was present in 18 cases and type 11 in four and type 33 in two. Twenty-three (53%) cases of genital region SK and one (3%) case of nongenital region SK contained HPV DNA sequences. Histopathologically, the perinuclear vacuolization of epithelial cells, mitosis and dyskeratotic cells were more marked in HPV DNA-positive SK than those in negative SK (P < 0.01). We suppose HPV may play an important role in epidermal proliferation of SK in the genital region.

Infundibular keratosis--a prototype of benign infundibular tumours

Three cases of a benign follicular tumour of infundibular origin are reported. The neoplasms were solitary, verrucous, slowly-growing papules or nodules on the face, which were diagnosed clinically as verruca vulgaris or seborrhoeic keratoses. Histologically, several epithelial lobules were seen, mainly above the level of the surface of the surrounding skin, with characteristic funnel-shaped invaginations. The tumours occasionally contained vellus hairs or were connected with sebaceous glands and/or hair follicles at their bases, indicating their follicular origin. The tumour masses consisted of peripherally arranged basaloid and inner squamoid cells. The latter cells contained more glycogen and appeared paler with haematoxylin and eosin (H&E) stains than the normal inter-follicular squamous cells. Neither clear cells nor squamous eddies were observed. Palisading of the basaloid cells was not a prominent feature. The name 'infundibular keratosis' is proposed for such tumours, which probably represent the prototype of infundibular tumours of the hair follicle.

Trichilemmal keratinization in seborrheic keratoses

In 33 of 112 seborrheic keratoses reviewed histologically, a keratinization process was observed, which was identical with or showed marked similarity to, trichilemmal keratinization (TK). This type of keratinization took place more frequently in lesions which were pruritic and in those located on the extremities. Histologically, the change was observed in the bottoms of pseudocysts and crypts, in areas showing evidence of inflammation, such as exocytosis, spongiosis and squamous eddy or whorl formation. No relationship was found between the presence of TK or TK-like keratinization and the various histologic types of seborrheic keratoses. It is concluded that a process which can not be distinguished from TK microscopically may occur frequently in seborrheic keratoses as a result of inflammation.

The relationship of seborrheic keratosis and basal-cell carcinoma?

Adjoining basal-cell carcinoma (BCC) and seborrheic keratosis (SK) are rarely reported despite the frequency of the two tumors. Unusual ulcerative changes in an SK are indications for biopsy.