Giant melanoacanthoma mimicking malignant melanoma

Melanoacanthoma denotes a rare variant of pigmented seborrheic keratosis. A 65-year-old male farmer had pigmented, verrucous, itchy, highly painful, progressively growing irregularly oval plaque on left side of lower back for the past five years. The indurated lesion, measuring maximum diameter 10 cm × 5 cm, had no discharge, bleeding, ulceration, or associated lymphadenopathy. Dermoscopy showed regular pigmentary network and cribiform pattern of ridges without any feature of malignant melanoma. Histopathology showed well-defined islands of basaloid cells interspersed with large and richly dendritic melanocytes. The lesion was totally excised followed by skin grafting. Our patient was unique in its massive size and clinical resemblance with malignant melanoma. The diagnosis was confirmed by dermoscopy and skin biopsy.     

Pigmented seborrheic keratoses of the vulva clinically mimicking a malignant melanoma: a clinical, dermoscopic-pathologic case study

The diagnosis of seborrheic keratosis is, in general, a clinical one, but in some cases, the differential diagnosis between pigmented seborrheic keratosis and malignant melanoma is difficult. Dermoscopy may improve the early diagnosis of vulvar melanoma and thus play a role in the preoperative classification of pigmented lesions at this particular site. We report the first case of a pigmented seborrheic keratosis of the vulva clinically mimicking a malignant melanoma, whose dermoscopic features have been investigated together with their pathologic correlates. Dermoscopically our case shows the absence of comedo-like openings and the presence of the pseudo-network. Dermoscopy is therefore a useful method for the differential diagnosis of pigmented lesions even in the vulva.     

Prevalence of melanoma clinically resembling seborrheic keratosis: analysis of 9204 cases

OBJECTIVE: To estimate the prevalence of melanoma clinically mimicking seborrheic keratosis. DESIGN: Retrospective review of cases submitted for histological examination with a clinical diagnosis of seborrheic keratosis or with a differential diagnosis that included seborrheic keratosis. SETTING: A tertiary medical care center-based dermatopathology laboratory serving academic dermatology clinics that have a busy pigmented lesion clinic. MATERIALS AND METHODS: A total of 9204 consecutive pathology reports containing a diagnosis of seborrheic keratosis in the clinical information field were identified between the years 1992 and 2001 through a computer database search. Reports with a final histological diagnosis of melanoma were selected for further review and clinicopathological analysis. MAIN OUTCOME MEASURE: Histological diagnosis, which was correlated with the preoperative clinical diagnosis. RESULTS: Melanoma was identified in 61 cases (0.66%) submitted for histological examination with a clinical diagnosis that included seborrheic keratosis. Melanoma was in the clinical differential diagnosis of 31 cases (51%). The remaining lesions had a differential diagnosis of seborrheic keratosis vs melanocytic nevus (17 cases, 28%), basal cell carcinoma (7 cases, 12%), or a squamous proliferation (3 cases, 5%). In 3 cases (5%), seborrheic keratosis was the only clinical diagnosis. All histological types of melanoma were represented. CONCLUSIONS: Our results confirm that melanoma can mimic seborrheic keratosis. These data strongly support the current policy of submitting for histological examination all specimens that have been removed from patients.     

Melanoma and seborrheic keratosis differentiation using texture features

Purpose: To explore texture features in two-dimensional images to differentiate seborrheic keratosis from melanoma.
Methods: A systematic approach to consistent classification of skin tumors is described. Texture features, based on the second-order histogram, were used to identify the features or a combination of features that could consistently differentiate a malignant skin tumor (melanoma) from a benign one (seborrheic keratosis). Two hundred and seventy-one skin tumor images were separated into training and test sets for accuracy and consistency. Automatic induction was applied to generate classification rules. Data analysis and modeling tools were used to gain further insight into the feature space.
Result and Conclusions: In all, 85–90% of seborrheic keratosis images were correctly differentiated from the malignant skin tumors. The features correlation_average, correlation_range, texture_energy_average and texture_energy_range were found to be the most important features in differentiating seborrheic keratosis from melanoma. Over-all, the seborrheic keratosis images were better identified by the texture features than the melanoma images.     

Melanoma mimicking seborrheic keratosis: an error of perception precluding correct dermoscopic diagnosis

Seborrheic keratosis is a common skin lesion that can usually be recognized either clinically or dermoscopically. However, melanomas mimicking seborrheic keratoses, as well as melanomas arising in association with seborrheic keratoses, have been described. We report the case of a patient with a lesion that initially revealed "classic" dermoscopic features of a seborrheic keratosis. However, during follow-up, changes in color developed within the center of the lesion that led the clinician to the correct diagnosis of melanoma. Upon retrospective evaluation of the baseline image of the lesion; the clinician was now able to "see" that which his brain could not appreciate on initial examination and to realize that the lesion had subtle features suspect for melanoma. This case represents a diagnostic pitfall due to errors in perception. Dermatologists should be cognizant of "errors in perception"; we suggest that a final dermoscopic judgment of a seborrheic keratosis be rendered by combining the gestalt diagnosis of the overall pattern, with deliberate dermoscopic analysis of all quadrants of the lesion.     

Occult Basal Cell Carcinoma Arising in Seborrheic Keratosis

The present study reports a case of an occult basal cell carcinoma that arose in seborrheic keratosis. The patient was a fifty-six-year-old male who presented with a dark brown plaque on his back. Clinically, the lesion demonstrated no nodules or ulcerations suggesting that it was malignant. However, histopathological analysis of the lesion revealed an atypical basaloid cell mass that appeared to be a solid basal cell carcinoma beneath and surrounded by a seborrheic keratosis lesion. Thus, the coexistence of basal cell carcinoma and seborrheic keratosis is possible and should be considered when a malignant change in seborrheic keratosis is apparent.     

Seborrheic keratosis with compound nevus, junctional nevus and basal cell carcinoma in the same lesion.

Seborrheic keratosis can be associated with different neoplasms such as basal cell carcinomas, squamous cell carcinomas and melanomas. We describe an unusual case of a man who presented with a brown plaque on his back. The clinical diagnosis was melanoma. Histopathologic examination of the lesion revealed four neoplasms: a compound nevus, a junctional nevus, a superficial basal cell carcinoma and a seborrheic keratosis. Although this association most likely represents a chance phenomenon, we discuss the possibility that the seborrheic keratosis developed from the nevus, and that subsequently the junctional nevus and the basal cell carcinoma developed from the seborrheic keratosis.     

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.     

A Possible Case of Eccrine Poroma Arising in Seborrheic Keratosis with Partial Intermediate Malignancy and Tumor of the Follicular Infundibulum

An eighty-year-old woman presented with a eccrine poroma that appeared to have arisen in a seborrheic keratosis lesion on the right side of her abdomen. The tumor consisted of a brownish, flat, elevated lesion with an eroded nodule at its periphery. Histopathological analysis of the flat, elevated lesion revealed benign basaloid and squamoid cells that showed acanthotic upward proliferation, suggesting a seborrheic keratosis. The eroded nodule showed irregular proliferation of slight atypical squamoid cells with, in parts, ductal structures in the upper dermis, suggesting that it was an eccrine poroma with partial intermediate malignancy. In addition to the eroded nodule, an occult tumor clinically accompanied the seborrheic keratosis. Histopathology of the occult tumor revealed fenestrated columns and cords of pale epithelial cells attached to the base of the seborrheic keratosis lesion, which was diagnosed as a tumor of the follicular infundibulum. Although reports of seborrheic keratosis transforming into a sweat gland tumor are rare, the present case suggests that seborrheic keratosis may develop into benign or malignant adnexal tumors, including sweat gland and follicular tumors. Thus, seborrheic keratosis should be considered as a possible precursor of adnexal tumor.     

Two Cases of Basal Cell Carcinoma Arising in Seborrheic Keratosis

The present study reports two cases of basal cell carcinoma arising in seborrheic keratosis. The first case is a seventy-three-year-old female who presented with a blackish nodule arising from a pigmented lesion on her chest. Histopathological analysis of the nodule and the pigmented lesion revealed a basal cell carcinoma with hair follicular differentiation and an acanthotic seborrheic keratosis, respectively. The second case is a seventy-year-old female with a blackish nodule arising from a pigmented lesion on her back. Histological analysis of the nodule revealed an atypical basaloid cell mass surrounded by a seborrheic keratosis lesion. In addition to the coexisting seborrheic keratosis with the basal cell carcinoma, a basaloid follicular hamartoma that showed muliple hamartomatous hair follicles or small cysts replaced by a branching cord or lace-like network of basaloid cells surrounded by fibrovascular stroma was identified. We concluded that both cases presented a rare combination of a seborrheic keratosis which underwent a malignant change to basal cell carcinoma. It appears that both basal cell carcinomas and seborrheic keratosis may derive from a similar source: pluripotential cells of either the epidermis or hair follicle epithelium.     

Fibroepitelioma de Pinkus. Descripción dermatoscópica de 3 casos

Fibroepithelioma of Pinkus is considered to be a rare variant of basal cell carcinoma with well-defined histopathological features.Clinical diagnosis often requires differentiation from benign lesions such as acrochordon, intradermal melanocytic nevus, neurofibroma, seborrheic keratosis, and even malignant lesions such as amelanotic melanoma. Dermoscopy of this type of lesion is not extensively described in the literature, though it usually presents certain specific characteristics that suggest the diagnosis and, therefore, an appropriate therapeutic approach.We present 3 cases of fibroepithelioma of Pinkus, describing their clinical, dermoscopic, and histopathological features.     

Dysplastic nevus associated with seborrheic keratosis

Seborrheic keratosis is a common skin lesion which may coincidentally be associated melanocytic nevi. The authors describe a case of dysplastic nevus associated with seborrheic keratosis and discuss the clinical, dermoscopic, and histological findings of this association. They also discuss the association between seborrheic keratosis and other benign and malignant tumours.     

Comedo-like openings in melanoma

We describe a case of melanoma with the presence of comedo-like openings at dermoscopy. These structures, typical of seborrheic keratosis, represent an uncommon finding in melanoma. We emphasize the importance of searching for specific dermoscopic criteria for melanocytic lesions during the examination of a pigmented lesion, despite possible observations of characteristic structures of non-melanocytic lesions, in order to increase the accuracy in the diagnosis of melanoma.     

Pedunculated malignant melanoma.

A woman had a primary pedunculated malignant melanoma. This is a rare form of presentation and may result in clinical confusion with seborrheic keratosis, fibroepithelial papilloma, or granuloma pyogenicum. The aggressive nature of the lesion was indicated by the presence of erosion and bleeding. Though the tumor cells were present only in the pedunculated mass, it had metastasized to regional lymph nodes at the time of surgery.     

共聚焦激光扫描显微镜在不典型汗管瘤中的应用

目的探讨皮肤共聚焦激光扫描显微镜(CISM)诊断汗管瘤的应用价值。方法对24例临床诊断为扁平疣、脂溢性角化病但不排除汗管瘤的患者,选定典型皮损做CLSM检查,后取该处皮损行组织病理学检查。结果 CLSM图像显示表皮大致正常,真皮浅层或中层可见圆形、卵圆形的高折光性结构,组织病理检查结果提示表皮大致正常,真皮内可见多数导管、小的囊腔及由上皮细胞所组成的小细胞巢及索,这与CLSM图像下的高折光性结构一致。结论 CLSM是诊断汗管瘤及鉴别扁平疣、脂溢性角化病等皮肤病非常有用的辅助工具。     

Biopsy guided by dermoscopy in cutaneous pigmented lesion - Case report

It may be clinically difficult to differentiate early-stage melanoma from benign tumors, specially pigmented seborrheic keratosis. Dermoscopy can help; however, the findings are not always conclusive. Therefore, histopathology may be necessary for a correct diagnosis. We describe a melanocytic lesion with dubious clinic and dermoscopic findings. An incisional biopsy of a suspicious area, guided by dermoscopy, was performed to clarify the findings.     

水通道蛋白3在四种皮肤肿瘤中的表达

目的 探讨水通道蛋白3（AQP3）在四种皮肤肿瘤组织中的表达及意义。方法 应用免疫组织化学方法检测30例脂溢性角化病、15例Bowen病、32例鳞状细胞癌、17例恶性黑素瘤及15例正常人皮肤组织中AQP3的表达。结果 脂溢性角化病、Bowen病、鳞状细胞癌、恶性黑素瘤及正常人表皮组织中均存在AQP3蛋白的表达;脂溢性角化病皮损中AQP3表达水平与正常人对照组差异无统计学意义（P > 0.05）;Bowen病、鳞状细胞癌及恶性黑素瘤皮损中AQP3蛋白表达显著高于正常人对照组（P < 0.01）,其中鳞状细胞癌与恶性黑素瘤的表达最强,均显著高于Bowen病（P < 0.01）,但鳞状细胞癌与恶性黑素瘤比较差异无统计学意义（P > 0.05）。此外,在鳞状细胞癌中AQP3的表达与肿瘤的分化有显著相关性（P < 0.01）;在已转移恶性黑素瘤中AQP3的表达显著高于未转移恶性黑素瘤（P < 0.05）。结论 AQP3在皮肤恶性肿瘤中表达上调。     

Inverted follicular keratosis simulating malignant melanoma

A 93-year-old woman was noted to have a single pigmented lesion on the posterior aspect of her neck. Clinical examination revealed a 12 x 8-mm flat lesion, with an irregular border and variegated pigmentation. Dermatoscopic examination revealed a lesion with multiple colours, featureless areas and black dots, suggestive of malignant melanoma. With a presumed clinical diagnosis of malignant melanoma, an elliptical excision was performed, with a 1-cm margin. However, histological examination revealed the unexpected diagnosis of pigmented inverted follicular keratosis.     

Pigmented malignant hidroacanthoma simplex mimicking irritated seborrheic keratosis

Pigmented variant of malignant hidroacanthoma simplex (PMHS) is very rare. We are aware of only two reported cases, all arising in pigmented hidroacanthoma simplex (HS). We report the third case of PMHS arising in a pigmented HS. A 71-year-old-woman presented with a well-demarcated pigmented hyperkeratotic tumor on the right knee resembling irritated seborrheic keratosis. Histopathologic examination of the excised tumor revealed intraepidermal proliferation of atypical polygonal poroid cells forming large, sharply demarcated nests with colonization of dendritic melanocytes. In addition, there were focal changes of a benign pigmented HS and syringofibroadenoma. The key diagnostic features of ductal structures and intracytoplasmic lumina were highlighted by carcinoembryonic antigen and epithelial membrane antigen immunostaining. PMHS should be differentiated from irritated seborrheic keratosis, melanoacanthoma, Bowen's disease and malignant melanoma both clinically and pathologically.     

共聚焦激光扫描显微镜鉴别脂溢性角化病与鲍恩病

目的：探讨共聚焦激光扫描显微镜（CLSM）在脂溢性角化病与鲍恩病鉴别中的应用价值。方法选88例临床诊断为脂溢性角化病和18例临床诊断为鲍恩病的患者典型皮损做CLSM检查,然后取该处皮损行组织病理学检查。结果脂溢性角化病CLSM图像特征：全部有表皮脑回状结构,另有角蛋白充填的囊性包裹体,表皮突呈小梁状下延;基底层细胞排列呈条索状或放射状9例,基底层及真皮层可见折光性明亮的结构6例。鲍恩病CLSM图像特征：表皮中下层细胞灶状排列紊乱,体积较大,细胞形态不规则,有明显的异形,真皮浅层散在单个核细胞浸润。结论脂溢性角化病与鲍恩病在CLSM成像上有不同的特征性,CLSM可为二者的鉴别诊断提供帮助。