The differential diagnosis of intraepidermal malignant lesions using immunohistochemistry

Pagetoid Bowen Disease Initially Misdiagnosed as Ectopic Extramammary Paget's Disease

Pagetoid Bowen disease is a histological variant of Bowen disease which demonstrates large pale staining cells (pagetoid cells). It requires differential diagnosis from other cutaneous malignancies with similar patterns, such as extramammary Paget's disease (EMPD) and Pagetoid melanoma in situ. Herein, we report a case of Pagetoid Bowen disease which was initially misdiagnosed as ectopic EMPD.

RANKL expression is a useful marker for differentiation of pagetoid squamous cell carcinoma in situ from extramammary Paget disease

BACKGROUND

Pagetoid squamous cell carcinoma in situ (SCCIS) is a histopathologic variant of SCCIS composed of cells that display an abundant, pale-staining cytoplasm in a pagetoid distribution within the epidermis. As pagetoid SCCIS is sometimes difficult to differentiate from extramammary Paget disease (EMPD) histopathologically, specific markers for pagetoid SCCIS or EMPD are needed by dermatopathologists.

METHODS

In this report, we employed immunohistochemical staining for receptor of activated nuclear factor kappa ligand (RANKL) and programmed death-ligand 1 (PD-L1) in six cases each of pagetoid SCCIS and EMPD.

RESULTS

The Paget cells strongly expressed RANKL in EMPD, whereas the atypical keratinocytes did not express RANKL in any of the six cases of pagetoid SCCIS. In all cases of pagetoid SCCIS, atypical keratinocytes expressed PD-L1. In EMPD, Paget cells expressed PD-L1 in half of the cases at a lower level of expression than was seen in the surrounding keratinocytes.

CONCLUSION

This study suggested that RANKL, but not PD-L1, could be a marker to differentiate between pagetoid SCCIS and EMPD.

Ultrastructural Examination of a Case of Pagetoid Bowen Disease Exhibiting Immunohistochemical Features in Common With Extramammary Paget Disease

A panel of immunohistochemical markers may be used to differentiate between pagetoid Bowen disease (PBD) and primary extramammary Paget disease (EMPD) in selected cases. Although diffuse staining with cytokeratin 7 (CK7), CAM5.2, carcinoembryonic antigen, epithelial membrane antigen (EMA), and gross cystic disease fluid protein 15 generally supports diagnosis of EMPD, cases have been reported where PBD also expressed CK7, EMA, and CAM5.2. Based on these findings, some authors suggested that the 2 entities may arise from the same multipotent stem cell, capable of further differentiation toward squamous and secretory lines. To the best of our knowledge, this issue has never been investigated by comparing PBD and EMPD at the ultrastructural level. We performed the first ultrastructural study of a case of PBD exhibiting common immunohistochemical features with EMPD. The lesion displayed some ultrastructural features often observed in Bowen disease and some that are typically found in EMPD. These findings indicate the presence of a bidirectional differentiation--secretory and squamous--within the same lesion, thus supporting the hypothesis that PBD and primary EMPD may arise from a common progenitor cell.

Doença de Paget pigmentada do mamilo simulando melanoma cutâneo: importância da imuno-histoquímica na diferenciação dessas doenças

A variante pigmentada da doença de Paget mamária é rara, com cerca de 12 casos relatados, e pode mimetizar clínica e histologicamente o melanoma. Como na forma clássica, em geral associa-se à neoplasia da mama acometida, com origem principalmente no carcinoma intraductal que se estende à epiderme através de ducto lactóforo. A fisiopatologia da hiperpigmentação permanece desconhecida. Relata-se o caso de paciente de 49 anos que apresentou lesão pigmentada do mamilo, suspeita de melanoma. O exame histológico não foi suficiente para confirmar o diagnóstico, sendo necessária realização de perfil imuno-histoquímico. Apesar de incomum, o diagnóstico de doença de Paget deve ser lembrado como diferencial de melanoma em lesões pigmentadas dessa região, em ambos os sexos.

Expression of cytokeratin subtypes in intraepidermal malignancies: a guide for differentiation

BACKGROUND

Among intraepidermal malignancies of epithelial origin, Bowen's disease, bowenoid actinic keratosis (BAK), intraepidermal malignant eccrine poroma (MEP), and Paget's disease may pose diagnostic difficulties.

METHODS

Histologic features and immunohistochemical profiles of 24 cases of Bowen's disease, 21 cases of BAK, 18 cases of intraepidermal MEP, and 11 cases of Paget's disease were analyzed.

RESULTS

Using multivariate logistic regression test, multinuclear giant cells and solar degeneration were found to be the only histologic parameters of diagnostic help. On the other hand, a widespread positive reaction for CK 5/8, CK 7, CK 19, and negative reaction for CK 10, was a helpful feature in the differentiation of Paget's disease from Bowen's disease and BAK. The widespread and strong expression of CK 10 was seen in almost all cases of Bowen's disease in contrast to BAK. The widespread expression of CK 5/8 and CK 7, and negative reaction for CK 10, was in favor of Paget's disease, compared to intraepidermal MEP. On the other hand, widespread expression of CK 19 was a common finding in intraepidermal MEP, in contrast to Bowen's disease.

CONCLUSION

An immunohistochemical panel may provide significant hints on the differentiation of common intraepidermal malignancies, especially in problematic cases.

Keratin profile of intraepidermal cells in Paget's disease, extramammary Paget's disease, and pagetoid squamous cell carcinoma in situ

BACKGROUND

Although the histopathologic differential diagnosis of pagetoid neoplasms is broad, unique histopathologic identifiers and clinical correlation can often identify the process. However, in the case of mammary Paget's disease (MPD) or extramammary Paget's disease (EPD) without an obvious underlying malignancy, distinction from pagetoid squamous cell carcinoma in situ (PSCCIS) can be challenging. Our goal was to better define the immunohistochemical staining patterns of these three entities in the hope of determining distinctive staining patterns.

METHODS

We evaluated nine cases of PSCCIS, five cases of MPD, and 10 cases of EPD with the immunohistochemical antibodies CAM 5.2 and CK 5/6. In addition, only PSCCIS was stained with CK 7, as the staining patterns of CK 7 in MPD and EPD are well known from prior studies.

RESULTS

CAM 5.2 diffusely stained all cases of MPD and EPD and failed to stain any case of PSCCIS. Furthermore, CK 7 only focally stained two of the 10 cases of PSCCIS. CK 5/6 was difficult to interpret due to the high functional background staining of the normal keratinocytes in the epidermis.

CONCLUSIONS

Based on these results, our data supports the use of CAM 5.2 and CK 7 immunoperoxidase markers in differentiating between difficult cases of PSCCIS and MPD or EPD. An antibody panel consisting of S-100, CAM 5.2, and CK 7 will aid in the accurate diagnosis of almost all pagetoid neoplasms of the breast or genital skin.

The ectopic expression of gastric mucin in extramammary and mammary Paget's disease

The immunohistochemical analysis of the ectopic expression of gastric mucin has been used as a valuable tool for the identification of several neoplasms. We performed an immunohistochemical examination of the expression of gastric, intestinal, and mammary-type mucins in 25 lesions from patients with extramammary Paget's disease (ExMPD) and in 10 lesions from patients with mammary Paget's disease (MPD). All ExMPD lesions were immunopositive for HGM-45, a marker of gastric surface mucous cells, whereas only 40% of MPD lesions were weakly immunopositive. No markers for gastric-gland mucous cells were found in almost all ExMPD and MPD lesions, and markers for intestinal mucin were recognized in only a few lesions. Antibodies specific for MUC1, a marker of mammary-type mucin, gave positive results in both ExMPD and MPD lesions at a higher frequency than antibodies specific for gross cystic disease fluid protein-15. Our analysis indicates that Paget's cells contain gastric surface-type mucin in ExMPD and they contain mammary-type mucin in both ExMPD and MPD. The ectopic localization of mucosubstances may be a further step in the understanding of these lesions. Moreover, antibodies against MUC1 seem to be a useful tool for the diagnosis of both ExMPD and MPD.

Mammary and extramammary Paget's disease

Mammary and extramammary Paget's disease are uncommon intraepithelial adenocarcinomas. Both conditions have similar clinical features, which mimic inflammatory and infective diseases. Histological diagnostic confusion can arise between Paget's disease and other neoplastic conditions affecting the skin, with the most common differential diagnoses being malignant melanoma and atypical squamous disease. The glandular differentiation of both mammary Paget's disease and extramammary Paget's disease is indicated by morphological appearances, the presence of intracellular mucin in many cases, and positive immunohistochemical staining for glandular cytokeratins, epithelial membrane antigen, and carcinoembryonic antigen. This article provides an overview of mammary and extramammary Paget's disease and discusses recent evidence regarding the cell of origin. The concepts of primary and secondary Paget's disease are presented and the differential diagnosis is discussed with reference to immunohistochemical markers that might be of diagnostic value.

Pagetoid bowen disease: a report of 2 cases that express cytokeratin 7

Bowen disease is a variant of squamous cell carcinoma in situ. In some cases a pagetoid growth pattern can be observed with cytologically atypical clear cells arranged singly and in nests. The differential diagnosis of pagetoid Bowen disease includes primarily Paget disease and malignant melanoma in situ, as well as other less common entities. Two cases of pagetoid Bowen disease are described, one in a 65-year-old man with a thigh lesion and the other in a 25-year-old man with a lesion in the penile/scrotal region. Neither patient had clinical evidence of an internal malignant neoplasm. In both cases, the neoplastic cells were positive for cytokeratin (CK) 7 and CK 19 and were negative for CK 18, CK 20, carcinoembryonic antigen, GCDFP-15, c-erbB2, S100, and HMB-45. In aggregate, these findings support the diagnosis of pagetoid Bowen disease. Previously, others have shown that CK 7 is an almost invariable marker of Paget disease. Thus, we report these two cases to illustrate that CK 7 can be expressed by pagetoid Bowen disease and should not be a cause of confusion in the differential diagnosis.

Amelanotic blue nevus: a variant of blue nevus

Blue nevi are typically heavily melanized. We report a variant of blue nevus that is minimally pigmented. Of the 1,358 blue nevi seen in our laboratory during the last 6 years, 38 (2.7%) were selected that had scant or absent melanin. We refer to these blue nevi as the amelanotic type. Approximately half of the cases in clinical diagnosis were nevus of some type, whereas other differential diagnoses were basal cell carcinoma, dermatofibroma, and lesion. Histologically all specimens were characterized by the spindle-shaped cells seen in blue nevi, but with very little or no obvious melanin. Some lesions were markedly cellular, resembling the features of cellular blue nevus. No hemosiderin was identified on Perls' stain, whereas Fontana-Masson stain was variably positive. Usually there was fibrous stroma. In most cases, the histologic differential diagnosis was dermatofibroma. Other histologic differential diagnoses included amelanotic and/or spindle cell melanoma, dermal Spitz nevus, neurofibroma, and scar. There was no pleomorphism or increased mitotic activity. Evidence of epidermal melanocytic hyperplasia was seen in two cases. Furthermore, the lesions had been present for many years without evidence of recent change. Immunohistochemistry showed all cases to be strongly positive with anti Mel-5 antibody, but only weakly positive or negative with anti S-100 and HMB-45 antibodies. We would like dermatologists and pathologists to be aware of this unusual and uncommon entity.

Margin control for lentigo maligna

BACKGROUND

Lentigo maligna is an in situ malignant melanoma for which the treatment of choice is surgical excision. The current recommendation is local resection with a 0.5 to 1.0 cm margin of normal skin. Because many lesions occur on the face, the narrowest possible margin reduces the amount of scarring. Controversy surrounds the use of Mohs micrographic surgery to preserve normal skin and resect the lentigo maligna.

OBJECTIVE

The purposes of this prospective study were to determine the narrowest possible margin of resection of lentigo maligna and the accuracy of frozen and fixed histologic specimens from those margins. In addition, the benefit of adjunctive immunoperoxidase staining with antibodies to S-100 protein and HMB-45 monoclonal antibody was examined retrospectively.

METHODS

A Wood's light was used to delineate the clinical margin in 16 cases of lentigo maligna that were resected with serial excisions 0.3, 0.6, 1.0, and 1.3 cm from the clinical border of the tumor. Frozen sections were confirmed by fixed histopathologic specimens. Subsequently these tissue blocks were examined with antibodies to S-100 protein and HMB-45 monoclonal antibodies. Patients were observed 5 to 9 years.

RESULTS

One of the 16 patients had a recurrence 8 years after surgery. Although lesions with a diameter less than 2.0 cm had narrower margins of resection, the majority of lesions were resected with a margin of 0.6 to 1.0 cm. Lesions larger than 3.0 cm in diameter required a margin of resection greater than 1.0 cm. The antibody to S-100 protein was neither sensitive nor specific enough to assist with identification of the process. HMB-45 monoclonal antibody was sensitive and assisted in the identification of atypical melanocytes.

CONCLUSION

The modifications of Mohs micrographic surgery including the use of fixed histopathologic specimens and the use of HMB-45 monoclonal antibody to help delineate atypical melanocytes offer the possibility of narrower margins of resection for lentigo maligna.

Patterns of cytokeratin expression by neoplastic and non-neoplastic epithelium

Eighty-one epithelial lesions were studied immunohistologically for cytokeratin protein expression using three anticytokeratins CAM 5.2, NCL5D3 and RCK102. Consistent differences were noted between squamous and glandular neoplasms. Squamous and cutaneous carcinomas were found to preferentially express higher molecular weight cytokeratins than adenocarcinomas. In addition, tumours of similar morphology from different sites showed differences in expression of these markers. Differences in pattern were also found between benign and malignant lesions in the case of liver and urinary bladder. Thus the value of cytokeratin profile analysis in characterisation of epithelial neoplasms is confirmed and may be useful in distinguishing benign from malignant tumours in some instances.

Ultrastructural study of extramammary Paget's disease--histologically showing transition from bowenoid pattern to Paget's disease pattern

Histological, immunohistochemical, and ultrastructural studies were performed on two cases of histologically unusual extramammary Paget's disease. Histologically, the central area of the lesions showed a bowenoid pattern, and the peripheral area showed typical extramammary Paget's disease. The transition zone showed an intermediate pattern. All these areas were positive for CEA and EMA, and negative for S-100 protein. Ultrastructurally, in the intermediate pattern, the tumour cells had abundant cytoplasmic glycogen, and the widened intercellular spaces contained numerous glycogen particles, which were probably secreted by the tumour cells. It is well known that eccrine glands, but not apocrine glands, secrete glycogen particles. Therefore, the present findings suggest that some cases of extramammary Paget's disease are a proliferation of germinative cells with eccrine gland differentiation.

Extramammary Paget's disease and prostatic carcinoma

A patient with perianal extramammary Paget's disease (EMPD) occurring simultaneously with prostatic adenocarcinoma is presented. Four previously reported cases of genital EMPD associated with prostatic carcinoma are reviewed. The use of immunohistologic techniques to help establish the diagnosis in some cases, and the relationship of EMPD to underlying adenocarcinoma of sweat glands and of the lower urinary and gastrointestinal tracts is discussed. The importance of a directed search for internal malignancy in the individual patient with EMPD is emphasised.

Immunohistochemical demonstration of keratin in ameloblastoma as an indication of tumor differentiation

Keratin expression was studied immunohistochemically in 27 ameloblastomas using polyclonal antibody against wide-spectrum keratins (TTL) and monoclonal antibodies against lower- and higher-molecular-weight keratins (PKK1 and KL1), respectively, to clarify the tumor differentiation. Reactions with TTL and KL1 antibodies were generally positive in the stellate cells of the follicular or acanthomatous ameloblastomas. Cell nests of the basal cell type were positive for PKK1. On the other hand, the reactions with TTL or KL1 in the plexiform type were generally weak or absent. From these facts, it was concluded that the follicular, as well as acanthomatous, ameloblastoma is liable to undergo squamous differentiation, whereas the plexiform ameloblastoma remains in primitive stage of tumor differentiation.

Pagetoid dyskeratosis: a selective keratinocytic response

Pale cells that resemble those of Paget's disease have been found within apparently normal epidermis in a variety of benign papules. Although they have been considered an artifact, they show characteristic premature keratinization. In contrast to other dyskeratotic processes they mature into orthokeratotic squamae. The histopathologic, ultrastructural and immunocytochemical features of these cells are illustrated, and the differential diagnosis is reviewed.

Paget's disease of the groin associated with adenocarcinoma of the urinary bladder

A 70-year-old Caucasian male developed a left groin tumor with epidermal infiltration of Paget's type. Five months later the ureter was found to be obstructed by a bladder adenocarcinoma cytologically identical to the skin lesion. Both tumors contained carcinoembryonic antibodies, using the immunoperoxidase method. Despite radiation therapy, the patient died a month later. There are no previous reports of association between urinary bladder adenocarcinoma and extramammary Paget's disease of the skin.

Antibody to S-100 protein aids the separation of pagetoid melanoma from mammary and extramammary Paget's disease

We evaluated the usefulness of immunohistological staining for S-100 protein in differentiating mammary and extramammary Paget's disease from primary malignant melanoma of superficial spreading (pagetoid) type. This technique was compared to both the mucicarmine and periodic acid-Schiff (PAS) methods. The tumor cells of 10 melanomas contained abundant cytoplasmic S-100 protein. In tissues from mammary and extramammary Paget's disease, S-100 protein was detected in myoepithelial cells, Langerhans cells, and Schwann cells of cutaneous nerves, but was not present in tumor cells. The mucicarmine stain was most useful for vulvar Paget's disease, mucicarminophilic material being present in 9/10 cases. In mammary Paget's disease, only 2/8 cases stained by the mucicarmine technique. Cytoplasmic PAS-positive material was present in the tumor cells of 9/10 cases of vulvar Paget's disease, but was noted in only 1/9 cases of mammary Paget's disease. Melanoma cells from two cases stained weakly with both mucicarmine and PAS indicating that these stains are not specific for Paget's disease in this comparison. The PAS and mucicarmine stains are helpful in differentiating anogenital Paget's disease from pagetoid melanoma, but are less useful in mammary Paget's disease. Immunohistological demonstration of S-100 protein provides an additional diagnostic tool to aid the separation of Paget's disease from pagetoid melanoma.