MITF::CREM-rearranged tumor: a novel group of cutaneous tumors with melanocytic differentiation.

Cutaneous tumors with melanocytic differentiation represent a broad group of neoplasms of both melanocytic and non-melanocytic origin. Besides traditional members such as clear-cell sarcoma (CCS) and PEComa, the latter group has recently expanded to also include MITF::CREM fusion-associated tumors, but the available data are limited. Herein, we present a third case of this rare neoplasm which occurred in the temporal region in a 1-year-old girl. It was an infiltratively growing polypoid dermal-based lesion lacking an intraepidermal component. It consisted of cellular solid sheets or small nests of epithelioid to spindled cells with a predominantly eosinophilic and much less commonly clear cytoplasm. The nuclei had round to ovoid shape and exhibited moderate to high-grade atypia and prominent nucleoli. The mitotic activity was 11 mitoses per 10 high-power fields, and atypical mitotic figures were present. Immunohistochemically, the tumor was strongly positive with S100 protein, SOX10, and MITF, while HMB45, tyrosinase, and Melan A were negative. Extensive molecular analysis revealed only MITF::CREM gene fusion. There had no evidence of disease 9 months after the diagnosis. These tumors need to be distinguished from malignant tumors with melanocytic differentiation, primarily from melanoma. However, additional cases still need to be studied to precisely define their biological potential and establish their nosologic status.

Tumor lesions of penis and scrotum according to WHO classification 2022.

Similarly to testicular tumors, key changes on penile and scrotal neoplasia were incorporated into WHO classification 2016. Therein, penile squamous cell carcinomas were divided into two groups based on the pathogenesis, namely HPV-associated and HPV-independent. This remains unchanged in WHO classification 2022. For those carcinomas where HPV status can not be determined, a category of squamous cell carcinoma NOS was added. Variants of squamous cell carcinoma, namely basaloid, papillary-basaloid, warty, warty-basaloid, clear cell and lymphoepithelioma-like carcinomas are not recognized as distinctive variants of HPV-associated group anymore. Similarly, squamous cell carcinoma, usual type, pseudohyperplastic, pseudoglandular, verrucous carcinoma, carcinoma cunniculatum, papillary, adenosquamous, sarcomatoid and mixed carcinoma are no more not recognized as distinctive variants of HPV-independent carcinomas. Instead, these variants are now called subtypes. Some previously distinct subtypes now belong to the morphological spectrum of other subtypes. Basaloid-papillary subtype belongs to basaloid squamous cell carcinoma and carcinoma cunniculatum is currently recognized as morphological variation of verrucous carcinoma. Pseudohyperplastic and mixed subtypes were removed from the classification. Adenosquamous carcinoma is currently termed adenosquamous and mucoepidermoid carcinoma and represents distinct entity. Precursor lesions of squamous cell carcinoma underwent substantial modifications in the WHO classification 2016 as well, and remain unchanged in WHO classification 2022. Terminology for HPV - induced lesions have been unified to low grade squamous intraepithelial lesions (LSIL) and high grade squamous intraepithelial lesions (HSIL). This classification applies to the whole anogenital area, including penis, anus, perianal region, vulva, vagina and uterine cervix. LSIL is further divided to condyloma accuminatum and (penile) intraepithelial neoplasia grade 1 (PeIN1), HSIL is divided to PeIN2 and PeIN3. Penile HPV-independent precursor lesions are named differrentiated penile intraepitelial neoplasia (dPeIN) and are identical to analogous lesions on vulva.

Psoriasis vulvae.

OBJECTIVE: Case presentation, differential dia-gnostic, possible therapeutic procedure and a brief literature report. CASE REPORT: An 84-year-old woman was repeatedly examined for chronic extended dermatologic lesion on lower abdomen, external genitals, perianal region, groin and adjacent inner thighs. CONCLUSION: Neither colposcopy with dermatovenerologic consultation, nor histopathological examination led to a precise conclusion. Only a special dermatopathologic expertise showed a dia-gnosis of inverse psoriasis with suggested therapy.

Oral presentation of paraneoplastic pemphigus as the first sign of tonsillar HPV associated squamous cell carcinoma. A case report.

BACKGROUND: Paraneoplastic pemphigus (PNP) in the oral cavity is a rare variant of blistering pemphigus disease closely associated with mostly malignant tumors. The diagnosis may even precede an underlying malignancy enabling early detection. Here, we describe a previously unreported case of PNP associated with HPV-related tonsillar squamous cell carcinoma. METHODS AND RESULTS: A 50-year-old woman was referred to a dentist because of painful oral lesions resembling aphthae major and minor. Later, blisters appeared and an incisional biopsy was performed. Histological examination revealed an unusual coexistence of subepithelial and intraepithelial blisters raising suspicion of paraneoplastic pemphigus. The patient underwent 18F-FDG PET/MRI, showing a metabolically active process in the left palatal tonsil. Diagnostic biopsy revealed HPV type 16 associated tonsillar squamous cell carcinoma. A left tonsillectomy with elective left-sided neck dissection was performed. The postoperative period was complicated by bilateral fluidothorax. Two weeks after radical tumor removal, the mucosal and skin lesions of PNP disappeared. The patient currently shows no evidence of recurrence either of malignancy or PNP eight months after the surgery. CONCLUSION: PNP is a rare autoimmune blistering disease characterized by polymorphous cutaneous and mucosal lesions associated with internal neoplasms including HPV associated squamous cell carcinoma of a tonsil. In order to identify an occult malignancy, a whole-body PET/CT or PET/MRI scan is recommended. Rarely, accurate patient management may depend on the dentist being familiar with this entity and on interdisciplinary cooperation involving dermatologist, radiologist, pathologist, and pneumologist. A strict patient follow-up is indicated.

VEILND (Video Endoscopic Inguinal Lymph Node Dissection) with Florescence Indocyanine Green (ICG): A Novel Technique to Identify the Sentinel Lymph Node in Men with ≥pT1G2 and cN0 Penile Cancer.

Introduction: In men with ≥pT1G2 cN0, penile cancer lymph node sampling is recommended with either (1) scintigraphically labelled Dynamic sentinel lymph node biopsy (DSLNB) or (2) modified inguinal lymph node dissection (MILND). Although DSLNB is a minimally invasive technique, the false negative rate can be about 10%, and a further operative procedure is required if positive. Open MILND is a diagnostic and therapeutic option but has a much higher morbidity. A potential compromise is the technique of LND-VEILND (video endoscopic inguinal LND) that can be combined with ICG florescence marking of sentinel lymph node (SLN). We present a pilot study of ICG-VEILND. The aim was to validate the applicability of a combination ICG marking of SLN in VEILND (to increase probability to excise SLN) and determine the optimal timing and dosage of ICG. Materials and Methods: 15 patients with VEILND (24 groins) underwent ICG application with fluorescence near-infrared (NIR 803⟶830 nm) detection. ICG is applied subcutaneously adjacent to the penile cancer or residual stump of penis or suprapubic region (in a history of total penectomy: 5 cases). The dose of 1.25 mg (ICG) was applied in one case with invisible SLN, the dose of 2.5 mg in 1 mL in 8 cases, and 5 mg in the remaining 6 patients (10 groins). Results: Failure of marking SLN with ICG occurred in 25.0% of cases (6/24): due to application of 1.25 mg ICG, extensive metastasis to SLN, in 4 cases, the cause was unknown (16.7%, 4/24). In the short follow-up period, no local recurrence was seen in the pN0 ICG group. Conclusion: Fluorescence infrared image with ICG dye increases the probability of removal of the SLN during VEILND. The dose of ICG is 2.5 (5) mg diluted in 1 ml and can be applied preoperatively even in the suprapubic region in men with a history of total penectomy, with an unexplainable failure of ICG marking in 16.7%.

Stewart-Treves syndrome: Case report and literature review.

Lymphangiosarcoma, or Stewart-Treves Syndrome (STS), is a very rare skin angiosarcoma with poor prognosis, which usually affects the upper limbs of patients who underwent breast cancer surgery, including axillary dissection followed by radiotherapy (RT). Cutaneous lymphangiosarcomas, which account for approximately 5% of all angiosarcomas, usually originate in the limb with chronic lymphedema. Lymphatic blockade is involved in the onset of STS. RT contributes indirectly to an increased risk of developing STS by causing axillary-node sclerosis and resulting in a lymphatic blockade and lymphedema. Chronic lymphedema causes local immunodeficiency, which indirectly leads to oncogenesis. Currently, axillary nodes are no longer routinely irradiated after axillary dissection, which is associated with a reduction in the incidence of chronic lymphedema from 40% to 4%. The use of sentinel lymph node biopsy technique is also widespread and the associated risk of lymphedema is further reduced. Thus, the incidence of STS decreased significantly with improved surgical and radiation techniques. The overall prognosis of STS patients is very poor. Only early radical surgical removal, including amputation or disarticulation of the affected limb, or wide excision at an early stage offers the greatest chance of long-term survival. Only a few case reports and series with a small number of patients with lymphangiosarcoma can be found in the literature. We present a case report of the first diagnosed STS at our department in an effort to highlight the need of the consideration of developing lymphangiosarcoma in patients with chronic lymphedema.

Comparison of the biomarkers for targeted therapies in primary extra-mammary and mammary Paget's disease.

BACKGROUND: Primary Extra-mammary Paget's disease (EMPD) is a very rare cutaneous adenocarcinoma affecting anogenital or axillary regions. It is characterized by a prolonged course with recurrences and eventually distant metastatic spread for which no specific therapy is known. METHODS: Eighteen EMPD (13 vulvar and five scrotal) and ten mammary Paget's disease (MPD) cases were comprehensively profiled for gene mutations, fusions and copy number alterations, and for therapy-relevant protein biomarkers). RESULTS: Mutations in TP53 and PIK3CA were the most frequent in both cohorts: 7/15 and 5/15 in EMPD; 1/6 and 4/7 in MPD HER2 gene amplification was detected in 4/18 EMPD (3 vulvar and 1 scrotal case) in contrast to MPD where it was detected in the majority (7/8) of cases. TOP2A gene amplification was seen in 2/12 EMPD and 1/6 MPD, respectively. Similarly, no difference in estrogen receptor expression was seen between the EMPD (4/15) and MPD (3/10). Androgen receptor was also expressed in the majority of both cohorts (12/16 EMPD) and (7/8 MPD).Here ARv7 splice variant was detected in 1/7 EMPD and 1/4 MPD cases, respectively. PD-L1 expression on immune cells was exclusively observed in three vulvar EMPD. In contrast to MPD, six EMPDs harbored a "high" tumor mutation burden (≥10 mutations/Mb). All tested cases from both cohorts were MSI stable. CONCLUSIONS: EMPD shares some targetable biomarkers with its mammary counterpart (steroid receptors, PIK3CA signaling pathways, TOP2A amplification). HER2 positivity is notably lower in EMPD while biomarkers to immune checkpoint inhibitors (high TMB and PD-L1) were observed in some EMPD. Given that no consistent molecular alteration characterizes EMPD, comprehensive theranostic profiling is required to identify individual patients with targetable molecular alterations.

Spectrum of Changes in Anogenital Mammary-like Glands in Primary Extramammary (Anogenital) Paget Disease and Their Possible Role in the Pathogenesis of the Disease.

To determine whether a subset of primary extramammary Paget disease (EMPD) may originate in anogenital mammary-like glands (AGMLG), the authors studied 181 specimens of EMPD, detailing alterations in AGMLG. The latter were identified in 33 specimens from 31 patients. All patients were women, ranging in age from 38 to 93 years (median, 65 y). In all cases, lesions involved the vulva and in 1 patient the perianal skin was affected. Histopathologically, AGMLG manifested changes identical to columnar cell change (CCC) (87.1%), usual ductal hyperplasia (22.6%), columnar cell hyperplasia (CCH) (9.7%), oxyphilic (apocrine) metaplasia (6.5%), and atypical duct hyperplasia (3.2%). Four cases (12.9%), in addition to intraepidermal carcinoma, harbored invasive carcinoma. In all 4 of these, AGMLG displayed a range of alterations including ductal carcinoma in situ, CCC, and CCH. Three further cases (9.7%) showed ductal carcinoma in situ without any definite invasive carcinoma. Colonization of AGMLG by neoplastic Paget cells was noted in 6 cases. As CCC and CCH may be encountered in normal AGMLG, these alterations are unlikely to play a significant role in the pathogenesis of the disease. However, by analogy with mammary Paget disease, rare cases of primary EMPD may originate in AGMLG with a subsequent upward migration of the neoplastic cells into the epidermis and possible later breach through the basal membrane. Usual ductal hyperplasia and atypical duct hyperplasia can then be regarded as earlier precursor lesions, linking both ends of the spectrum.

Acquired elastotic hemangioma-like changes and eccrine sweat duct squamous metaplasia in lichen simplex chronicus/prurigo nodularis-like lesions of the knee and elbow.

BACKGROUND: The so-called acquired elastotic hemangioma (AEH) represents a peculiar vascular lesion affecting the sun-damaged skin of the extensor surface of the forearms or the lateral aspect of the neck of middle-aged or elderly women. METHODS: This is a clinicopathological and immunohistochemical study of a series of 6 lesions located on the knee or elbow showing epithelial features of lichen simplex chronicus (LSC)/prurigo nodularis (PN) with a marked subepidermal vascular proliferation closely resembling AEH. RESULTS: Microscopically, all cases of cutaneous lesions showed epithelial features of LSC/PN, that is compact hyperkeratosis with focal parakeratosis, irregular acanthosis, prominent hypergranulosis. Moreover, a marked subepidermal vascular proliferation arranged in a horizontal band closely resembling AEH was detected in these lesions. Another common histopathological finding was eccrine duct squamous metaplasia and/or hyperplasia. CONCLUSIONS: While AEH represents a distinctive clinicopathological variant of hemangioma characteristically appearing on sun-exposed areas of middle-aged or elderly patients, the herein described lesions seem to be non-neoplastic epithelial, vascular and eccrine sweat duct reactive changes which are likely to be associated with chronic pressure or repeated mechanical stimulation with a marked predilection for the knee and elbow.

Study of Selected BRCA1, BRCA2, and PIK3CA Mutations in Benign and Malignant Lesions of Anogenital Mammary-Like Glands.

Anogenital mammary-like glands (AGMLGs) are nowadays considered a normal component of the anogenital area. Lesions involving AGMLGs are histopathologically very similar to their mammary counterparts, but the information on molecular biological mechanisms in these vulvar/perianal tumors is scarce. Mutations in the PI3K-AKT cascade have been found in hidradenoma papilliferum. The authors studied selected BRCA1, BRCA2, and PIK3CA mutations in series of benign and malignant neoplasms thought to be associated with AGMLGs, including 9 cases of primary extramammary Paget disease, 3 different cases of mammary-type carcinoma (adenoid cystic like, tubulolobular, and invasive ductal like), and 5 cases of hidradenoma papilliferum. No BRCA mutation was detected, whereas 3 neoplasms yielded PIK3CA mutation, including extramammary Paget disease, mammary-type invasive ductal carcinoma, and tubulolobular carcinoma. Our study expands the spectrum of lesions of AGMLGs harboring mutations in genes encoding the PI3K-AKT cascade. Further studies of the whole BRCA1 and BRCA2 genes using a larger cohort are needed to clarify their role in the pathogenesis of AGMLG lesions.

Squared-Off Nuclei and "Appliqué" Pattern as a Histopathological Clue to Periocular Sebaceous Carcinoma: A Clinicopathological Study of 50 Neoplasms From 46 Patients.

The histopathological diagnosis of periocular sebaceous carcinoma can be difficult in poorly differentiated cases showing few mature sebocytes. The authors examined 50 periocular sebaceous carcinomas from 46 patients to determine the frequency of 2 features seen in this neoplasm, namely cells with squared-off nuclei and so-called "appliqué" pattern (peritumoral subnecrosis of peripherally located neoplastic cells). Neoplastic cells with squared-off nuclei were found in varying numbers in both the intraepithelial and dermal (invasive) components in all neoplasms, whereas the appliqué pattern was observed in a third of the cases. It is concluded that these features, taken together, may serve as a clue for the diagnosis of periocular sebaceous carcinoma.

Differentiated squamous intraepithelial lesion (dSIL)-like changes in the epidermis overlying anogenital melanocytic nevi: A diagnostic pitfall.

BACKGROUND: Differentiated squamous intraepithelial lesion (dSIL) is morphologically and immunohistochemically analogous in the whole anogenital region. dSIL is a premalignant lesion frequently misinterpreted histopathologically as a benign dermatosis. The authors describe a peculiar change in the basal cell layer of the epidermis/epithelium overlying anogenital melanocytic nevi that may histopathologically imitate dSIL. The aim of this study is to familiarize the pathologists with this pitfall to avoid its possible overdiagnosis as dysplasia. Further, we tried to explore the biological characteristics of the dSIL-like changes and to focus on the differential diagnostic aspects. DESIGN: Seventy cases of anogenital nevi were retrieved from our registry. All cases were stained with hematoxylin and eosin (H&E) and reviewed. Cases in which the epidermis overlying nevi featured atypical appearing basal keratinocytes in otherwise fully differentiated epithelium, variable degrees of acanthosis and parakeratosis were selected for additional investigation. RESULTS: Thirty cases meeting the above described criteria were identified. The patients were 8 males and 22 females, with age at the time of diagnosis ranging from 4 to 68years. Follow-up data were available for 28 patients (range 0.5-19years, mean 5.1), and to date, no signs of epithelial malignancy have been recorded. Immunohistochemically (IHC), the epidermis overlying nevi showed insignificant positivity for p53 in all tested cases. Melanocytic markers (S-100 protein, SOX10, Melan A) and cytokeratin AE1/3 labeled melanocytes and keratinocytes, respectively, enabling their distinction, especially in nevi featuring a junctional component. CONCLUSIONS: Differentiated squamous intraepithelial lesion-like changes seem to occur relatively often in the epidermis overlying anogenital melanocytic nevi. Since morphologically they are virtually identical to the "true" dSIL, their distinction largely depends on p53 expression in basal keratinocytes with normal p53 expression in dSIL-like changes and diffuse nuclear/p53-null immunostaining in the "true" dSIL serving as an essential differential diagnostic tool. dSIL-like alterations seem to have no malignant potential, as to date, none of the patients included in this study have shown any signs of epithelial malignancy.

Anogenital Mammary-Like Glands: A Study of Their Normal Histology With Emphasis on Glandular Depth, Presence of Columnar Epithelial Cells, and Distribution of Elastic Fibers.

The normal histology of anogenital mammary-like glands (AGMLG) has been studied previously, but some aspects, including glandular depth, presence of columnar epithelium resembling columnar cell change/hyperplasia as defined in mammary pathology, and distribution of elastic fibers, have not been previously investigated. To address these issues, we studied 148 AGMLG identified in 133 paraffin blocks sampled from 64 vulvar wide excision or vulvectomy specimens (64 patients, various indications for surgery). The depth of AGMLG ranged from 0.64 to 3.9 mm. Epithelial columnar cell change was noted in 33.1% of all AGMLG, whereas columnar cell hyperplasia was detected in 10.1%. Occasionally, combinations of cuboidal epithelium and columnar cell change were seen within 1 histological section. Of 22 specimens stained for elastic fibers, in only 6 (27.3%) cases were elastic fibers found around glands. Periductal elastic fibers were demonstrated around 3 of the only 5 ducts, which were available for analysis in slides stained for elastic fibers. The depth of AGMLG should be taken into account when planning topical and surgical therapies for lesions derived or evolving from AGMLG. Alterations identical to columnar cell change may represent a normal variation of AGMLG.

Cutaneous Sebaceous Lesions in a Patient With MUTYH-Associated Polyposis Mimicking Muir-Torre Syndrome.

A 76-year-old white male with a history of adenocarcinoma of the rectosigmoideum and multiple colonic polyps removed at the age of 38 and 39 years by an abdominoperitoneal amputation and total colectomy, respectively, presented with multiple whitish and yellowish papules on the face and a verrucous lesion on the trunk. The lesions were surgically removed during the next 3 years and a total of 13 lesions were investigated histologically. The diagnoses included 11 sebaceous adenomas, 1 low-grade sebaceous carcinoma, and 1 squamous cell carcinoma. In some sebaceous lesions, squamous metaplasia, intratumoral heterogeneity, mucinous changes, and peritumoral lymphocytes as sometimes seen in sebaceous lesions in Muir-Torre syndrome were noted. Mutation analysis of the peripheral blood revealed a germline mutation c.692G>A,p.(Arg231His) in exon 9 and c.1145G>A, p.(Gly382Asp) in exon 13 of the MUTYH gene. A KRAS mutation G12C (c.34G>T, p.Gly12Cys) was detected in 1 sebaceous adenoma and a NRAS mutation Q61K (c.181C>A, p.Gln61Lys) was found in 2 other sebaceous adenomas. No germline mutations in MLH1, MSH2, MSH6 and PMS2 genes, no microsatellite instability, no aberrant methylation of MLH1 promoter, and no somatic mutations in MSH2 and MSH6 were found. An identical MUTYH germline mutation was found in the patient's daughter. Despite striking clinicopathological similarities with Muir-Torre syndrome, the molecular biologic testing confirmed the final diagnosis of MUTYH-associated polyposis.

Cutaneous hidradenoma: a study of 21 neoplasms revealing neither correlation between the cellular composition and CRTC1-MAML2 fusions nor presence of CRTC3-MAML2 fusions.

Twenty-one hidradenomas from 20 patients (13 female, 7 male) ranging in age from 18 to 87years (mean, 57.75years; median, 60years) were studied for CRTC1-MAML2 and CRTC3-MAML2 fusions to find out whether there is a correlation between the particular cell type (polyhedral eosinophilic, clear, mucinous, epidermoid, and oncocytic) and presence the above alterations. CRTC1-MAML2 fusions were detected in 10 of the 21 neoplasms (47.6%). Fluorescence in situ hybridization for MAML2 break apart was analyzable in 13 specimens and in all these specimens was positive, including 4 tumors with no demonstrable CRTC1-MAML2 fusion. In none of the cases was a CRTC3-MAML2 fusion detected. No obvious correlation between the cellular composition and presence of t(11,19) translocation was found.

Human papillomavirus infection and p16 expression in the immunocompetent patients with extragenital/extraungual Bowen's disease.

BACKGROUND: The role of human papillomaviruses (HPV) in the development of squamous cell carcinoma (SCC) has been established for anogenital lesions but still remains controversial for carcinomas in other sites. The aim of this study was to determine the α-HPV and ß-HPV prevalence and their association with p16 expression, sun exposure, and clinicopathological findings in patients with Bowen's disease (BD). METHODS: One hundred sixty nine skin biopsy specimens from 157 immunocompetent patients with extragenital/extraungual BD were examined for HPV status and p16 expression. The presence of koilocyte-like changes, solar elastosis and papillomatosis was recorded for each specimen. RESULTS: BD was diagnosed more often in potentially sun-exposed sites with prevalence 73.6 % and a remarkable predilection for the head and neck region. High risk α-HPV or ß-HPV were detected in 34.7 % of lesions and ß-HPV infections dominated over α-HPV. Higher prevalence of koilocyte-like changes and papillomatosis was found in HPV-positive specimens but it was not statistically significant. The expression of p16 was detected in 79.8 % of lesions and displayed no correlation with the HPV status. HPV-positivity tended to be detected more often in sun-protected sites. Dual infections by α-HPV/ß-HPV genera and mixed α-HPV infections were not detected, while 37.5 % of ß-HPV positive specimens were infected by two or more ß-HPV genotypes. HPV 9 was significantly associated with mixed ß-HPV infections. CONCLUSIONS: HPV may play an etiological role at least in some SCC in situ arising in extragenital sites. Sunprotected sites may be more dependent on HPV-mediated co-carcinogenesis than sun exposed areas. The presence of the p16-expression, papillomatosis or koilocyte-like change is not a reliable marker of HPV infection in SCC in situ.

Bilateral Gigantomastia, Multiple Synchronous Nodular Pseudoangiomatous Stromal Hyperplasia Involving Breast and Bilateral Axillary Accessory Breast Tissue, and Perianal Mammary-Type Hamartoma of Anogenital Mammary-Like Glands: A Case Report.

Mammary-type fibroepithelial lesions involving ectopic breast and anogenital region are rare and usually coexist with normal orthotopic breast. We present what we believe to be a unique case of synchronous bilateral gestational gigantomastia resembling fibrous mastopathy, synchronous rapidly growing pregnancy-associated nodular pseudoangiomatous stromal hyperplasia involving right breast and bilateral axillary ectopic breast tissue, and metachronous perianal mammary-type hamartoma involving anogenital mammary-like glands occurring in a 34-year-old patient with facioscapulohumeral muscular dystrophy. Also, we review the literature concerning these lesions.

Hidradenoma Papilliferum: A Clinicopathologic Study of 264 Tumors From 261 Patients, With Emphasis on Mammary-Type Alterations.

Hidradenoma papilliferum (HP), also known as papillary hidradenoma, is the most common benign lesion of the female anogenital area derived from anogenital mammary-like glands (AGMLG). HP can be viewed conceptually as the cutaneous counterpart of mammary intraductal papilloma. The authors have studied 264 cases of HP, detailing various changes in the tumor and adjacent AGMLG, with emphasis on mammary-type alterations. In many HP, the authors noticed changes typical for benign breast lesions, such as sclerosing adenosis-like changes, usual, and atypical ductal hyperplasia. Almost in a third of cases, remnants of AGMLG adjacent to the lesion were evident, manifesting columnar changes reminiscent of those seen in breast lesions. This study shows that the histopathological changes in HP run a broad spectrum comparable with that in the mammary counterpart and benign breast disease.

Hybrid Epithelioid Schwannoma/Perineurioma.

We report a case of a 58-year-old who woman presented with a solitary slowly growing subcutaneous nodule covered by normally appearing skin on her left groin. Microscopically, the lesion was well circumscribed but unencapsulated, and showed biphasic cellular differentiation. One cell population was presented by small rounded (epithelioid) cells arranged singly, in small aggregates or short cords, whereas the second one was composed of cells with slender nuclei and delicate elongated bipolar cytoplasmic processes. On immunohistochemistry, the epithelioid component showed positive reaction for S-100 protein and negative for epithelial membrane antigen (EMA), thus compatible with schwannian differentiation and resembling epithelioid schwannoma. The other component showed a reverse immunophenotype being S-100 protein negative and EMA positive, thus corresponding to perineuriomatous differentiation. The clinicopathologic and immunohistochemical features of the lesion were compatible with hybrid epithelioid schwannoma/perineurioma, a rare morphological variant of peripheral nerve sheath tumors.