Primary cutaneous lymphomas (CL) in children is rare. Only a few studies focused specifically on paediatric CL and therefore little is known whether primary CL in children are similar to or different from their adult counterparts with respect to the clinicopathological presentation, behaviour and prognosis. An extensive literature search using PubMed/MEDLINE from January 1995 through July 2014 was undertaken for articles reporting cases of paediatric CL. In addition, we identified 31 children with CL in our institutions. Mycosis fungoides and lymphomatoid papulosis are the two most prevalent lymphoma forms in children. A few entities of cutaneous lymphomas such as cutaneous diffuse large B-cell lymphoma leg type, and Sézary syndrome have not been reported so far in children. Other lymphoma entities such as hydroa vacciniforme-like lymphoma are mostly seen in certain geographic areas (Asia, Central and South America). In the paediatric population, low-malignant indolent forms such as primary cutaneous marginal zone lymphoma and primary cutaneous follicle centre lymphoma are very rare, whereas the more aggressive forms of B-cell lymphomas, precursor lymphoblastic lymphomas, and blastic plasmacytoid dendritic cell neoplasm are the most common forms in children, mostly involving the skin secondarily. Most paediatric lymphomas have similar clinicopathological features and course as their adults counterparts, particularly in the group of cutaneous T-cell lymphomas. The spectrum of cutaneous B-cell lymphomas in children significantly differs from the one in adults. Diagnostic work-up and treatment of paediatric patients with lymphomas are best achieved in close collaboration with paediatric haematopathologists and oncologists.

We present six cases of a distinctive soft tissue tumor which occurred in five women and one man. None of the patients had signs of neurofibromatosis. All tumors occurred on the fingers ( n=5) or the thenar eminence of the hand ( n=1). The mean age of the patients was 33 years. The tumors were 1-2.5 cm in diameter (mean size 1.6 cm). Three patients with follow-up were without signs of recurrence or metastasis. Microscopically the lesions were nonencapsulated and featured a multilobular architecture and both myxoid and pseudocystic change. The lobules varied in size and shape and were separated by variably thickened, dense, sclerotic/collagenous septae. The lobules were composed of two components: schwannomatous and perineuriomatous. The schwannomatous component was immunohistochemically S-100 protein positive and CD34 and EMA negative, and the perineuriomatous component had the appearance of retiform perineurioma. The perineurial parts were mostly S-100 protein and CD34 negative and EMA positive. These two components either formed separate nodules or the schwannomatous tissue surrounded the perineurial parts located in the centers of the lobules. We interpreted the lesions as hybrid tumors with features of schwannoma and retiform perineurioma.

Both patients were men with nodular lesions on the face. Histologically, the lesions were composed predominantly of variably maturated plasma cells with monotypic expression of immunoglobulin (Ig) lambda chains. Polymerase chain reaction for IgH genes did not reveal clonal rearrangement. Our cases are discussed in the context of previously reported cases of PCP with a long-term follow-up. We also include a review of all cases of PCP with known tumor progression earlier in the course of the disease (local relapse or visceral spread) to determine the clinical course of this primary cutaneous lymphoma.

The authors report a small series of sebaceous carcinoma developing in nevus sebaceus of Jadassohn (also known as organoid nevus) and analyze similar cases reported in the literature. All of our patients were females (age range 57-71 years; median 60 years) who had the organoid nevus on the scalp, face, or nuchal area, the rest of which was recognized clinically and/or histologically. All sebaceous carcinomas manifested unquestionable architectural (asymmetry, invasive growth) and cytological features of a carcinoma (cellular and nuclear pleomorphism, plentiful atypical mitoses, necroses en masse), demonstrated unambiguous sebaceous differentiation in the form of mature sebocytes, and lacked other differentiations. The sebaceous carcinoma was always accompanied by other benign or malignant adnexal lesions such as sebaceoma, syringocystadenoma papilliferum, syringocystadenocarcinoma papilliferum, trichoblastoma, tricholemmoma, desmoplastic tricholemmoma, or syringoma. In three cases, prominent mucinous metaplasia of sweat ducts and glands was seen. In two of these cases, sweat ducts exhibited hyperplastic changes. The analysis of the previously published material and our cases indicates that sebaceous carcinoma arising in organoid nevus has a female predilection and tends to occur in elderly patients. It may involve any site where nevus sebaceus typically occurs. Clinically, the tumor presents as a solitary nodule, ulcerated tumor, or mass, often with a recent history of rapid growth. It may arise alone, but it occurs more frequently as part of multiple benign and malignant adnexal tumors. The lesion does not seem to be associated with Muir-Torre syndrome. The rest of organoid nevus is usually recognized both clinically and microscopically, although large tumors may overgrow and mask the nevus. The tumor seems to be a low-grade carcinoma in terms of clinical behavior.

Multiple familial trichoepitheliomas (MFT) constitute an autosomally inherited syndrome possibly related to Brooke-Spiegler syndrome (BSS). Although some early studies suggested a role for the PTCH gene on chromosome 9q22.3 in the etiopathogenesis of MFT, recent studies of occasional patients with the MFT clinical phenotype identified mutations in the CYLD gene on chromosome 16q12-q13, a gene responsible for BSS. A systematic investigation of PTCH and CYLD mutations in patients with MFT has never been performed. Our main objective was to collect a reasonably large series of patients with MFT to (1) study the clinicopathological spectrum of the disease, (2) determine whether the PTCH gene is implicated in the pathogenesis of MFT, and if so (3) determine the relative frequency of CYLD and PTCH mutations, (4) establish if there may be any possible genotype-phenotype correlations, and (5) study the spectrum of somatic mutations. Clinical analysis including family histories, histopathological investigations, and molecular genetic studies were performed. There were 9 female and 7 male patients ranging in age from 11 to 63 years. They presented with multiple, small, discrete and sometimes confluent, skin-colored to pink, asymptomatic nodules preferentially located on the face, being especially prominent and confluent in the nasolabial folds and inner aspects of the eyebrows. A total of 66 conventional trichoepitheliomas (TEs) were studied microscopically. Aside from typical features of TE, some also exhibited variant morphological patterns including areas reminiscent of other benign adnexal neoplasms and melanocytic hyperplasia. In none of the 9 patients tested was a germline mutation of the PTCH gene identified. Germline CYLD mutations were detected in 6 of 13 patients tested (identical in 2 unrelated patients) including 2 novel mutations, whereas the remaining 7 individuals showed wild-type alleles. Two patients with germline wild-type CYLD showed, however, a somatic mutation in the gene (1 duplication, 1 substitution mutation). Neither CYLD nor PTCH germline mutations were found in the 5 patients in whom both genes were analyzed. MFT seems to be a phenotypic variant of BSS. The PTCH gene is rarely, if ever, involved in the pathogenesis of MFT. Absence of a germline mutation of the CYLD gene in cases harboring a somatic mutation may be explained by large deletions in the gene or by mutation in intronic sequences or in the promoter region. Considering our 5 patients with no mutation in either gene, the final possibility is that another, as yet undescribed gene (neither CYLD nor PTCH) is implicated in the pathogenesis of some patients with MFT.

Skin adnexal type tumors situated in the parenchyma of the breast are very rare. We report herein a case of solid-cystic hidradenoma of the breast. The tumor was situated in the parenchyma of the breast of a 55-year-old female and showed no connection to the overlying skin on ultrasound and radiology investigations, grossly and microscopically. Histologically, the tumor was identical to its cutaneous counterpart and was surrounded by breast tissue. The neoplasm was composed of solid and cystic areas. The cystic component, which predominated in the lesion, was filled with homogeneous eosinophilic material. The solid component consisted of several nodules with vague lobulated architecture protruding into the cystic spaces. The nodules were composed of cuboidal monomorphous cells that were continuous with larger polygonal cells and rare, large mucinous cells with basophilic granular cytoplasm. Several mammary ducts in close proximity to the tumor showed features of columnar cell hyperplasia. A 120-bp METC1/MAML2 fusion transcript was identified by RT-PCR and subsequent sequencing technique. This t(11;19) translocation has been reported in approximately 50% of hidradenomas of the skin.

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