Low-grade Adnexal Carcinoma of the Skin With Multidirectional (Glandular, Trichoblastomatous, Spiradenocylindromatous) Differentiation

The conjoint occurrence of follicular, sebaceous, or apocrine differentiations in a cutaneous adnexal neoplasm is a known event, more often encountered in benign neoplasms, whereas reports of cutaneous malignant adnexal tumors with bilineage or trilineage differentiation are few. A new case of a cutaneous malignant adnexal neoplasm with multidirectional differentiation is reported here. A 57-year-old woman presented with a long-standing, slowly growing, asymptomatic solitary tumor the size of a large nut in the coccygeal area, which was surgically excised. Ten years after the surgery, there was no evidence of recurrence or metastasis. Microscopically, the neoplasm was located in the dermis with focal extension into the subcutis. It was asymmetric, horizontally oriented, and mostly composed of small nodules that varied in shape from round and oval aggregations to elongated strands and irregular islands; the nodules were either clustered, formed a jigsaw puzzle-like pattern or were dispersed. The nodules were composed of small basaloid cells sometimes intermixed with larger cells with ample cytoplasm forming glandular structures. Rare nodules resembled elements seen in a spiradenoma by containing scattered lymphocytes and globules of hyalinized eosinophilic basal membrane material. The stroma was paucicellular, but focally it resembled that seen in perifollicular mesenchyme. Mitotic figures, including abnormal ones, were infrequent, but mild nuclear pleomorphism, nuclear crowding, and individual cell necrosis were easily appreciable in both small basaloid cells and cells with clear cytoplasm. Perineural invasion was apparent. We classified this tumor as a well-differentiated adnexal carcinoma demonstrating combined follicular and apocrine differentiation. It differs from previously published cases of malignant adnexal tumors with multidirectional differentiation and further exemplifies the spectrum of diversity encountered in malignant proliferations with differentiation toward the folliculosebaceous-apocrine unit.

Spindle cell predominant trichodiscoma: a fibrofolliculoma/trichodiscoma variant considered formerly to be a neurofollicular hamartoma: a clinicopathological and immunohistochemical analysis of 17 cases

Seventeen solitary nasal tumors that fulfilled all diagnostic criteria of so-called neurofollicular hamartoma, apart from distinct S100-positivity, were compared histopathologically and immunohistochemically with seven typical trichodiscomas from a similar clinical setting. Both the S100-negative neurofollicular hamartoma-like tumors and the trichodiscomas expressed an identical CD13-positive/CD34-positive fibrocytic immunophenotype without co-expression of neural/perineural (S100, neurofilament, epithelial membrane antigen), myogenic (desmin, calponin, muscle-specific actin, and alpha-smooth muscle actin), or melanocytic (S100, HMB45, NKI/C3, MelanA) epitopes. Histopathologically, there was striking morphologic overlap between trichodiscoma and S100-negative neurofollicular hamartoma-like tumor, apart from a highly characteristic fascicularly organized cellular fibrocytic stroma in the latter. We conclude that fibrofolliculoma/trichodiscoma and neurofollicular hamartoma-like tumor are morphologic variants of a single hamartomatous entity in which neurofollicular hamartoma-like tumor occupies the cellular pole of the morphologic spectrum. The entity formerly known as neurofollicular hamartoma appears to be nothing but a particularly cellular trichodiscoma with a distinctively organized stroma composed of CD34-positive fibrocytes. We therefore propose the new term spindle cell predominant trichodiscoma (SCPT) for this particular variant of the morphologic fibrofolliculoma/trichodiscoma spectrum.

Spindle Cell Hemangioma and Epithelioid Hemangioendothelioma Arising in an Area of Lymphedema

We report the case of a 73-year-old female patient with a multifocal vascular tumor that we regard as composite hemangioendothelioma (CHE). The lesions developed in an area of lymphedema. CHEs are rare vascular tumors in which various types of hemangioendothelioma are combined in 1 lesion. In the present case, separate tumors with histologic features of spindle cell hemangioma and features resembling epithelioid hemangioendothelioma were clustered in 1 anatomic region.

Myopericytoma of skin and soft tissues: clinicopathologic and immunohistochemical study of 54 cases

Perivascular neoplasms comprise traditionally glomus tumor and hemangiopericytoma (HPC). Whereas glomus tumor represents a well-defined entity, the existence of HPC as a separate entity has been questioned because a number of neoplasms of different lines of differentiation are characterized by a HPC-like vascular growth pattern. Myopericytoma represents a recently delineated entity showing a HPC-like vascular pattern. A large series of myopericytoma of skin and soft tissues has been analyzed to further characterize the clinicopathologic spectrum of this entity. Fifty-four cases of myopericytoma of skin and soft tissues were retrieved and the histology reviewed. Immunohistochemical stainings using alpha-smooth muscle actin (ASMA), desmin, and h-caldesmon antibodies were performed, and clinical data and follow-up information were obtained from referring pathologists. Thirty-four patients were male and 18 were female (gender was unknown in 2 cases). Patient age ranged from 13 to 87 years (median, 52 years). The lower extremities were most commonly affected (26 cases) followed by the upper extremities (16 cases), the head and neck region (4 cases), and the trunk (2 cases); exact location was unknown in 5 cases. In 20 cases, the neoplasms were confined to the dermis, in 6 cases an extension into the subcutis was seen, and 24 as well as 4 cases arose in subcutaneous and deep soft tissue, respectively. Two cases were multicentric; and in 1 of these patients, multiple anatomic regions were involved. Histologically, in all cases, numerous thin-walled vessels and a concentric, perivascular arrangement of ovoid, plump spindled to round myoid tumor cells was seen. However, a broad morphologic spectrum ranging from hypocellular, fibroma-like (3 cases), myofibroma-like (2 cases), angioleiomyoma-like (12 cases), and HPC-like neoplasms (13 cases) to classic myopericytomas (14 cases) and immature, cellular lesions (2 cases) was noted. In addition, 2 neoplasms with focal glomoid features, 5 intravascular, and 1 malignant myopericytomas were found. Prominent cytologic atypia and increased proliferative activity (>3 mitoses/10 high power fields) was seen in 4 and 2 cases, respectively. Immunohistochemically, all cases tested stained positively for ASMA. In addition, 29 of 32 cases tested stained positively for h-caldesmon, whereas desmin was only focally positive in 3 of 33 cases. Follow-up information was available in 46 cases (range, 7-168 months; median, 48 months). Despite marginal or incomplete excision in 23 of 46 cases, only 2 neoplasms (1 malignant and 1 intravascular myopericytoma) recurred locally (within 1 and 4 years, respectively). Despite overlapping morphologic features to angioleiomyoma and myofibroma, myopericytoma represents a distinct perivascular, myoid neoplasm of skin and soft tissues, characterized by a broad morphologic spectrum of concentrically, perivascularly growing myoid tumor cells that stain positively for ASMA and often for h-caldesmon, whereas desmin is usually negative. Most cases of myopericytoma behave in a benign fashion, but local recurrences and rarely metastases may occur in atypical and malignant neoplasms.

Two mitosis-specific antibodies, MPM-2 and phospho-histone H3 (Ser28), allow rapid and precise determination of mitotic activity

Mitotic figure (MF) counting is important in the evaluation of many tumor types. Inadequate fixation, crush artefacts, the presence of many apoptoses, or the rarity of MFs in a given lesion can make the determination of the mitotic index a very time-consuming or even impossible task, especially for novices. We evaluated the potential of the two commercially available mitotic markers MPM-2 and Phospho-Histone H3 Ser28 (PHH3) for improving mitotic counting. Formalin-fixed tissue of 1 lymphoma, 19 epithelial, 25 mesenchymal, and 10 melanocytic tumors was immunohistochemically stained with both antibodies. Mitotic counts of each tumor sample were determined by a pathologist and three residents in the hematoxylin and eosin and in both immunohistochemical stainings. Because of the higher sensitivity of the immunohistochemical stainings for MFs, average mitotic counts per 10 HPF were higher with MPM-2 (11.0) and PHH3 (10.1) than with hematoxylin and eosin (5.9) staining. The precise distinction of MFs from apoptoses and the visualization of the distribution of MFs uncovering mitotic hotspots, even at low magnification, turned out to be major advantages of both mitotic markers. In addition, the average time needed to establish the mitotic count was reduced by 40.3% with MPM-2 and by 50.4% with PHH3. MPM-2 and PHH3 were subjectively rated by all pathologists involved in this study to be very helpful in mitotic counting, especially in melanocytic and mesenchymal lesions but less so in epithelial tumors. Both markers have hence been successfully introduced in our laboratory for the routine assessment of MFs in melanocytic and mesenchymal tumors.

Infantile hemangioma is a proliferation of LYVE-1-negative blood endothelial cells without lymphatic competence

Infantile hemangiomas are common benign vascular tumors that exhibit a characteristic history of rapid proliferation in the first year of life and slow spontaneous involution during early childhood. The causative pathogenic event responsible for the abnormal endothelial proliferation remains elusive. The recent discovery of an immature phenotype of proliferating hemangioma endothelial cells due to the exclusive expression of the lymphatic endothelial hyaluronan receptor LYVE-1 led to the proposal that infantile hemangiomas are the result of a primary defect in endothelial cell maturation. To test this hypothesis, we looked for the expression of the lymphatic endothelial cell-specific markers LYVE-1, Prox-1, podoplanin and D2-40 in beta4 integrin-negative proliferating and beta4 integrin-positive involuting infantile hemangiomas. As beta4 integrin proved to be a suitable marker for staging infantile hemangiomas, we used it in combination with clinical and histological criteria to objectively determine the proliferative and involutional phases. In immunohistochemical and immunofluorescent stains, hemangioma vessels were negative for all lymphatic endothelial cell-specific markers tested during both proliferation and involution. LYVE-1 immunoreactivity, however, was found in the dense network of perivascular HLA-DR-positive cells with dendritic cell morphology that are supposed to play a role in hemangiogenesis by releasing pro- and antiangiogenic factors. Notably, this LYVE-1 staining failed to correlate with the growth status of infantile hemangiomas. Our results do not support the notion that LYVE-1 expression was restricted to the proliferative phase and downregulated during involution. Thus, LYVE-1 does not seem to be a reliable marker for proliferating infantile hemangiomas. We conclude that the suggested intrinsic defect in endothelial cell maturation is unlikely the cause for the post-natal rapid growth in infantile hemangiomas. In addition, the lack of lymphatic endothelial cell-specific markers implies that infantile hemangiomas are tumors of blood vessels without lymphatic competence.

Cutaneous lymphoid hyperplasia and other lymphoid infiltrates of the breast nipple: a retrospective clinicopathologic study of fifty-six patients

This study characterizes the clinicopathological spectrum of lymphoproliferations involving the breast nipple and/or areola. Morphologic, immunohistochemical, molecular-genetic, and clinical features of 58 specimens from 56 patients were analyzed. They were re-diagnosed as cutaneous lymphoid hyperplasia (CLH, n = 44); other benign lymphoid infiltrates (OBLI, n = 8); peripheral T-cell lymphoma, not otherwise specified (n = 1); cases with overlapping features of CLH and B-cell lymphoma (n = 3), one of them composed of spindle cells. Cutaneous lymphoid hyperplasia infiltrates were dense, composed mainly of B cells forming follicles with germinal centers (GC). Cutaneous lymphoid hyperplasia frequently showed features suggesting a malignancy as coalescing follicles with non-polarized germinal centers lacking mantle zones, and smudged infiltrates of lymphoid cells spreading into collagen (often as "Indian files"), smooth muscle, vessel walls, and nerve sheaths. Only two cutaneous lymphoid hyperplasias recurred; otherwise all patients are without disease (mean follow-up 62 months). Monoclonal rearrangement of immunoglobulin heavy chain gene was detected in five, and of T-cell receptor gamma gene in two cutaneous lymphoid hyperplasias using polymerase chain reaction (PCR), but the patients fared well too. In 47% of cases Borrelia burgdorferi was detected by polymerase chain reaction and/or serology, of which one was monoclonal. We conclude that cutaneous lymphoid hyperplasia is the most common lymphoproliferation of the breast nipple, rarely recognized clinically, and often overdiagnosed histologically as lymphoma.

Dendritic cell neurofibroma with pseudorosettes lacks mutations in exons 1-15 of the neurofibromatosis type 2 gene

Dendritic cell neurofibroma with pseudorosettes (DCNWPR) is a recently proposed variant of neurofibroma with a distinctive microscopic appearance that is produced by a pseudorosette pattern formed by small, dark, lymphocyte-like cells (Type I cells) arranged concentrically around larger cells, with pale-staining vesicular nuclei and copious faintly eosinophilic cytoplasm (Type II cells). Although DCNWPR appears not to be associated with neurofibromatosis (NF), 1 patient with DCNWPR has been described and suggested to have a form of NF because of multiple skin lesions, with 2 of them being DCNWPR as confirmed histologically. The aim of this study was to find out whether the neurofibromatosis type 2 (NF2) gene is mutated in DCNWPR. Seven histologically proven cases of DCNWPR, from which a substantial amount of archival paraffin-embedded material was available, were selected for this study. Three cases have been previously reported, including the intraneural lesion, and 4 cases were newly identified. There were 3 female and 4 male patients, ranging in age from 30 to 61 years (median, 48 yrs). All patients clinically presented with a small solitary lesion that was clinically diagnosed as fibroma or neurofibroma, and none of the patients had signs of NF. Follow-up was known for 6 patients (range, 1-5 yrs; median, 2.5 yrs) and was uneventful in each case. Microscopically, all lesions fulfilled the criteria for DCNWPR. Exons 1 to 15 of the NF2 gene were amplified by PCR using primers previously published. The amplified fragments were purified and sequenced. The obtained sequences were computer analyzed and compared with the data of the GenBank database. No mutation was identified in 5 analyzed samples from which suitable DNA had been extracted. DCNWPR appears to have no mutation in exons 1-15 of the NF2 gene. Given the relatively small number of cases studied, it seems premature to declare that a mutation of the NF2 gene is not involved in DCNWPR, as the possibility cannot be excluded that mutations were present but remained undetected because they occurred in exons that were not examined.

Distinct sets of genetic alterations in melanoma

BACKGROUND

Exposure to ultraviolet light is a major causative factor in melanoma, although the relationship between risk and exposure is complex. We hypothesized that the clinical heterogeneity is explained by genetically distinct types of melanoma with different susceptibility to ultraviolet light.

METHODS

We compared genome-wide alterations in the number of copies of DNA and mutational status of BRAF and N-RAS in 126 melanomas from four groups in which the degree of exposure to ultraviolet light differs: 30 melanomas from skin with chronic sun-induced damage and 40 melanomas from skin without such damage; 36 melanomas from palms, soles, and subungual (acral) sites; and 20 mucosal melanomas.

RESULTS

We found significant differences in the frequencies of regional changes in the number of copies of DNA and mutation frequencies in BRAF among the four groups of melanomas. Samples could be correctly classified into the four groups with 70 percent accuracy on the basis of the changes in the number of copies of genomic DNA. In two-way comparisons, melanomas arising on skin with signs of chronic sun-induced damage and skin without such signs could be correctly classified with 84 percent accuracy. Acral melanoma could be distinguished from mucosal melanoma with 89 percent accuracy. Eighty-one percent of melanomas on skin without chronic sun-induced damage had mutations in BRAF or N-RAS; the majority of melanomas in the other groups had mutations in neither gene. Melanomas with wild-type BRAF or N-RAS frequently had increases in the number of copies of the genes for cyclin-dependent kinase 4 (CDK4) and cyclin D1 (CCND1), downstream components of the RAS-BRAF pathway.

CONCLUSIONS

The genetic alterations identified in melanomas at different sites and with different levels of sun exposure indicate that there are distinct genetic pathways in the development of melanoma and implicate CDK4 and CCND1 as independent oncogenes in melanomas without mutations in BRAF or N-RAS.

Genomic analysis of blue nevi and related dermal melanocytic proliferations

Blue nevi are benign dermal melanocytic proliferations that can sometimes share overlapping microscopic features with melanoma. We used comparative genomic hybridization to analyze three groups of dermal melanocytic proliferations. Group 1 consisted of 10 cellular blue nevi and 1 deep penetrating nevus, none of which showed chromosomal aberrations. Group 2 consisted of 11 lesions that were histopathologically ambiguous. Three of these lesions demonstrated chromosomal aberrations (three or fewer per lesion). Group 3 consisted of seven histopathologically malignant lesions, each showing three or more chromosomal aberrations. Moderate to severe cytologic atypia and a mitotic rate of three or more mitoses per 10 high power fields were present in six of eight (75%) lesions that had at least three chromosomal aberrations but were absent in 15 of 20 (75%) lesions without chromosomal aberrations. Necrosis was present in four of the 29 (13%) lesions, with every lesion with necrosis demonstrating three or more genomic abnormalities. In conclusion, histopathologically unequivocally benign or malignant dermal melanocytic proliferations show nonoverlapping patterns of chromosomal aberrations. Ambiguous lesions can be separated into lesions with and without chromosomal aberrations. Future studies with clinical follow-up are necessary to determine which aberrations are most informative for classification of these lesions.

Reticular and plexiform perineurioma: clinicopathological and immunohistochemical analysis of two cases and review of perineurial neoplasms of skin and soft tissues

Perineurioma represents a recently described and relatively rare neoplasm in the spectrum of benign peripheral nerve sheath tumours composed of perineurial cells staining immunohistochemically positive for epithelial membrane antigen (EMA). In addition to intraneural, extraneural and sclerosing perineurioma, rare variants of perineurioma may occur, and their knowledge is important in the differential diagnosis of mesenchymal tumours of different lines of differentiation and clinically more aggressive neoplasms. We present a case of deep-seated reticular perineurioma arising on the upper arm of a 34-year-old female and a case of a dermal plexiform perineurioma arising on the lower lip of a 60-year-old female. The diagnosis was confirmed in both cases immunohistochemically; neoplastic cells stained positively for EMA and for the newly described perineurial markers, claudin-1 and glut-1. The morphological spectrum and the differential diagnosis of perineurial neoplasms of skin and soft tissues are discussed.

Carcinoid-like pattern in sebaceous neoplasms: another distinctive, previously unrecognized pattern in extraocular sebaceous carcinoma and sebaceoma

This report emphasizes a carcinoid-like pattern, a previously unrecognized feature in cutaneous sebaceous neoplasms. We report 7 patients with sebaceous tumors in which neoplastic cells were arranged in a trabecular and ribbon-like pattern or formed rosettes/pseudorosettes. The cases included 6 men and 1 woman, with their ages at the diagnosis ranging from 43 to 87 years (median age, 59). All patients presented with a solitary lesion. Locations were the scalp (n = 6) and forearm (n = 1). The carcinoid-like arrangement of neoplastic cells was the sole pattern in 4 cases, and in 3 cases the so-called labyrinthine/sinusoidal and/or rippled patterns were seen in addition. Sebaceous differentiation in the form of mature sebocytes varied from almost none to approximately 10%. Although the neoplasm appeared benign architecturally, the presence of cytologic atypia qualified 2 tumors as low-grade carcinomas. Four lesions represented sebaceomas, and in 1 case microscopic delineation between a carcinoma and sebaceoma was difficult. No neuroendocrine differentiation was demonstrated immunohistochemically, histochemically, and ultrastructurally. Electron microscopic examination performed in 1 case of carcinoma revealed lipid vacuoles in a minority of cells. There were no membrane-bound neuroendocrine granules. Rare cells contained peculiar large helioid inclusions. We conclude that the carcinoid-like pattern is another distinctive pattern indicative of sebaceous neoplasms. This pattern seems to be closely related to the rippled and labyrinthine/sinusoidal patterns, as exemplified by our cases, in which these arrangements sometimes occurred simultaneously.

Histiocytoid Sweet syndrome: a dermal infiltration of immature neutrophilic granulocytes

OBJECTIVE

To describe a series of 41 patients with fresh lesions of Sweet syndrome in which the histopathologic study demonstrated an inflammatory infiltrate mostly composed of histiocytoid mononuclear cells.

DESIGN

Histopathologic, immunohistochemical, and cytogenetic studies of the inflammatory infiltrate in a case series of histiocytoid Sweet syndrome.

SETTING

University departments of dermatology and a private laboratory of dermatopathology.

METHODS

Conventional histopathologic study as well as immunohistochemical investigations were performed using the alkaline phosphatase antialkaline phosphatase technique with a large panel of antibodies. In some cases, fluorescent in situ hybridization studies were performed to investigate the presence of the bcr/abl gene fusion.

RESULTS

Immunohistochemical studies demonstrated that most cells of the infiltrate showed immunoreactivity for CD15, CD43, CD45, CD68, MAC-386, HAM56, and lysozyme, which is consistent with a monocytic-histiocytic immunoprofile. However, intense myeloperoxidase reactivity was detected in most of the cells with histiocytic appearance, which raised the possibility of specific cutaneous involvement by myelogenous leukemia. Nevertheless, cytologic peripheral blood examinations, fluorescent in situ hybridization studies to investigate the bcr/abl gene fusion, and follow-up of the patients, taken all together, ruled out this possibility.

CONCLUSIONS

This case series demonstrates that some fresh cutaneous lesions of Sweet syndrome are histopathologically characterized by an infiltrate mostly composed of cells that may be misinterpreted as histiocytes, when in fact they are immature myeloid cells. We named this histopathologic variant histiocytoid Sweet syndrome, which should not be mistaken with leukemia cutis or other inflammatory dermatoses that are histopathologically characterized by histiocytes interstitially arranged between collagen bundles of the dermis.

Mucinous Carcinoma of the Skin, Primary, and Secondary

We present the largest series of mucinous carcinoma involving the skin, describing the histopathologic, immunohistochemical, electron microscopic, and cytogenetic findings. Our aim was fully to characterize the clinicopathologic spectrum and compare it with that seen in the breast. In addition, we wished to reevaluate the differential diagnostic criteria for distinguishing primary mucinous carcinomas from histologically similar neoplasms involving the skin secondarily, and study some aspects of their pathogenesis. We demonstrate that primary cutaneous mucinous carcinomas span a morphologic spectrum compatible to their mammary counterparts. Both pure and mixed types can be delineated morphologically, and some lesions have mucocele-like configurations. Most lesions seem to originate from in situ lesions that may represent, using mammary pathology terminology, ductal hyperplasia, atypical ductal hyperplasia, or ductal carcinoma in situ or a combination of the three. Inverse cell polarity appears to facilitate the progression of the changes similar to lesions in the breast. The presence of an in situ component defines the neoplasm as primary cutaneous, but its absence does not exclude the diagnosis; although for such neoplasms, full clinical assessment is essential. Mammary mucinous carcinoma involving the skin: all patients presented with lesions on chest wall, breast, axilla, and these locations can serve as clue to the breast origin. Microscopically, cutaneous lesions were of both pure and mixed type, and this correlated with the primary in the breast. Dirty necrosis was a constant histologic finding in intestine mucinous carcinomas involving the skin, and this feature may serve as a clue to an intestinal origin.

Paraneoplastic pityriasis lichenoides in cutaneous lymphoma: case report and review of the literature on paraneoplastic reactions of the skin in lymphoma and leukaemia

Paraneoplastic dermatoses are non-neoplastic skin disorders which occur in the context of an underlying malignant neoplasm. The classic paraneoplastic dermatoses are mostly associated with solid internal malignancies. They only rarely occur in the context of nodal or primary cutaneous lymphomas. Apart from these classic paraneoplastic dermatoses, there are additional skin disorders reported to occur in close association with haematological and lymphoproliferative disorders which can thus be regarded as paraneoplastic manifestations. We report for the first time two patients with pityriasis lichenoides et varioliformis acuta in association with mycosis fungoides. In addition, we review the literature on paraneoplastic dermatoses of the skin which have been described in patients with leukaemias and primary cutaneous lymphomas.

Cutaneous clear cell myomelanocytic tumour: a new member of the growing family of perivascular epithelioid cell tumours (PEComas). Clinicopathological and immunohistochemical analysis of seven cases

AIMS

To analyse seven cases of cutaneous myomelanocytic tumour histologically and immunohistochemically. Perivascular epithelioid cell tumours (so-called PEComas) are rare and recently delineated neoplasms occurring in the lung, kidney, pancreas, uterus, falciform ligament, vulva, heart, prostate and soft tissues. PEComas are characterized by a perivascular location of neoplastic cells showing a broad spectrum of epithelioid and spindled cells with clear, and granular pale eosinophilic cytoplasm, and a variable expression of melanocytic and muscle markers, whereas S100 protein and cytokeratins are usually absent.

METHODS AND RESULTS

We report seven cases of cutaneous myomelanocytic tumour arising on the lower (six cases) and upper (one case) extremities of female adults (age range 30-66 years). In all cases an ill-defined dermal lesion with extension into subcutaneous tissue was noted. The neoplasms contained numerous blood vessels with a lace-like pattern and slightly thickened vessel walls, and were composed of perivascular epithelioid cells containing clear or focally granular pale eosinophilic cytoplasm and round vesicular nuclei with small, sometimes slightly enlarged nucleoli. Increased proliferative activity and tumour necrosis were not seen. Immunohistochemically, tumour cells stained positively for HMB-45, microphthalmia transcription factor, and NKIC3 in all cases, whereas perivascular expression of alpha-smooth muscle actin and focal positivity for desmin were noted in one case each only. Two out of four cases tested stained focally positive for calponin. No expression of S100 protein and pancytokeratin was present. Despite incomplete/marginal excision in three cases none of the neoplasms has recurred locally so far.

CONCLUSIONS

With the presented series of cutaneous myomelanocytic tumours the clinicopathological spectrum of PEComas is expanded.

Hidradenoma Papilliferum with Oxyphilic Metaplasia

Reported here are 18 cases of hidradenoma papilliferum with oxyphilic metaplasia. All patients were women ranging in age from 29 to 74 years. Each presented clinically with a small, solitary tumor in the anogenital region. Microscopically, in addition to classic histopathological features, in every case there was oxyphilic metaplasia of the constituent epithelial cells. This finding could be likened to apocrine metaplasia, a term used in breast pathology. Other histopathological findings observed in this series, analogous to benign breast disease, included sclerosing adenosis-like changes, atypical apocrine adenosis-like changes, changes corresponding to usual ductal epithelial hyperplasia, epitheliomatosis with a streaming growth pattern, lamprocyte-like changes, clear cell change of the myoepithelium, foamy histiocyte reaction, and stromal fibrosis. Immunohistochemistry inferred that in the majority of cases oxyphilic metaplasia resulted from more lysosomes, whereas numerous mitochondria were detected in only 3 cases. Using 2 different PCR methods we identified HPV in 4 of 15 cases of hidradenoma with oxyphilic metaplasia. In addition, HPV was detected in 3 of 16 conventional papillary hidradenomas used as a control group. The following HPV types were identified: 16, 31, 33, 53, and 56. The last type was found in 5 cases. More than one HPV type from a single lesion was seen in 5 cases. Our observations are consistent with previous publications noting similarities between tumors of the breast and sweat glands. Oxyphilic metaplasia, areas with solid growth, and changes simulating atypical apocrine adenosis are rare and poorly recognized in hidradenoma papilliferum and may cause diagnostic difficulties; in our cases several submitting pathologists suspected malignancy. A causal role for HPV in hidradenoma papilliferum cannot be confirmed from our results, as the detection rate is too low. The exact role of the HPV in etiology and pathogenesis of this neoplasm has yet to be determined.

Multinucleate cell angiohistiocytoma: a new case report

Multinucleate cell angiohistiocytoma (MCAH) was first described by Smith and Wilson-Jones in 1985. It is an uncommon entity but probably underdiagnosed because of lack of recognition by clinicians and pathologists. We report a 47-year-old man with asymptomatic grouped violaceous papules on the dorsum of the hands for 3 years. The histopathological and immunopathological features of our case revealed characteristics of MCAH similar to the initial description of Smith and Wilson-Jones and other reports.

Follicular malignant melanoma: a variant of melanoma to be distinguished from lentigo maligna melanoma

Follicular malignant melanoma can be regarded as a rare and unique presentation of melanoma. It is characterized by a deep-seated follicular structure in which atypical melanocytes extend downward along the follicular epithelium and permeate parts of the follicle as well as the adjacent dermis. The clinical diagnosis of follicular malignant melanoma may be difficult because the tumor mostly resembles a comedo or a pigmented cyst. We studied five cases of follicular malignant melanoma in which the patients were between 61 and 82 years old. Three lesions were localized on the nose, one on the cheek, and one on the back of the neck. Clinically, all five cases measured distinctly less than 0.5 cm in size. While lentigo maligna is traditionally known as a pigmented macule in actinically damaged skin that gradually evolves in a slow process before invasive growth, three follicular malignant melanomas had developed in relatively short timeframes of 9 months to 1 1/2 years. In all five cases the inconspicuous clinical appearance did not herald a malignant melanoma with invasive growth. Follicular malignant melanoma underlines the importance of a correct excision technique with subsequent histologic workup and diagnosis. Superficial shave excision or even laser treatment in these specific cases may lead to a fatal prognosis for the patient.

Zirkumskripte akrale Hypokeratose

Circumscribed acral hypokeratosis is a rare chronic disorder of cornification that occurs predominantly in women. Lesions are solitary and do not respond to any local conservative treatment. They have to be differentiated by biopsy from other non-healing lesions and tumors in acral skin. Clinically lesions appear as sharply circumscribed reddish macules. The histologic hallmark is a circumscribed loss of the entire stratum corneum, which can be best demonstrated at the border of the lesion as a contrast to the perilesional broad stratum corneum typical for acral sites.