Induction of cutaneous hyperplasias by altered stroma

Dilated pore of Winer in a dog

A 9-year-old male neutered Goldendoodle was presented to the Animal Medical Center of Seattle with a history of a firm, hairless, cystic mass on the dorsal aspect of the neck. The mass had been present for 2 years and would periodically rupture and discharge moderate quantities of yellow-green, soft, semi-solid, keratinaceous material. As rupture of the mass was reported to cause the patient significant pain and discomfort, it was surgically excised. Histopathology of the mass revealed a bulbous keratin-filled cyst that communicated with the external environment via a small ostium. At the base of the cyst, the cyst lining was characterized by a markedly irregular and hyperplastic stratified squamous epithelium with an overt stratum granulosum and prominent, irregularly sized, shaped and spaced rete ridges. At the superficial aspect of the cyst near the ostium, the cystic lining was characterized by a relatively thinner stratified squamous epithelium with an overt stratum granulosum and regular basal contour. Based on the histomorphological appearance of the mass, a diagnosis of a dilated pore of Winer was made. Dilated pores of Winer are follicular cysts arising from the infundibulum of the hair follicle. They are relatively common in humans and uncommon in cats, and single case reports have been described in a horse and a woodchuck (Marmota monax). To the best of the authors' knowledge, this is the first description of a dilated pore of Winer in a dog.

Glandular Schwannoma With Apocrine Decapitation Secretion: A True Divergent Differentiation or Entrapped Normal Tissue?

ABSTRACT

We report an unusual case of schwannoma with glandular elements that demonstrated apocrine decapitation secretion. The glandular structures were embedded within the tumor, varied in shape and size, and were lined by a double-to-multilayered epithelium, with the inner layer composed of monomorphous cuboidal to columnar cells, focally with apocrine decapitation secretion, and the outer layer representing myoepithelial cells. A normal eccrine unit was observed near the lesion. Immunohistochemical studies showed that all luminal cells of the glandular structures stained positive for CK7, whereas myoepithelial cells expressed S100 and p63, and epithelial membrane antigen highlighted the luminal border. CK20 and neuroendocrine markers were negative in the glandular elements.Our findings suggest that the origin of the glandular elements in our case was represented by entrapped glands. Two theories may explain the epithelial hyperplasia observed in the present case as follows: the obstructive effect theory and the inductive ability of a mesenchymal proliferation to produce epidermal or adnexal changes. We suggest that, in a subset of cases, the origin of the glandular elements might represent entrapped glands, wherein their histomorphology/cytomorphology recapitulates the elements comprising the normal adjacent tissue. Further research is necessary to elucidate the histogenesis of glandular schwannoma.

Cutaneous eccrine inflammation and necrosis: review of inflammatory disorders affecting the eccrine apparatus including new associations

Despite being frequently overlooked during the examination of histopathological sections, eccrine sweat glands can offer clues for diagnosing various skin conditions. They provide important functions and can lead to several diseases when inflamed or injured. This review article provides information regarding eccrine physiology as well as well-established and novel entities that occur in association with eccrine gland pathology.

Ciliated and Mucinous Adenomatous Syringometaplasia: The Missing Link of the "Ciliated Eccrine Metaplasia" Theory in the Histogenesis of Cutaneous Eccrine Ciliated Cyst?

ABSTRACT

A variety of metaplastic changes has been reported in eccrine ducts and glands with squamous and mucinous syringometaplasia representing the most common histopathologic patterns. In the current case, a previously unreported variant of syringometaplasia was described in a female newborn with a 2-cm occipital cutaneous defect consistent with cutis aplasia. Over a more than 1-year period of local treatment, an enlarging plaque associated with local alopecia developed at the site of the original ulcerated area. A local excision demonstrated a superficial hypertrophic scar associated with a complete loss of hair follicles. In addition, there was a proliferation of eccrine glands and ducts lined by cuboidal epithelial cells arranged in a linear distribution beneath the scar area. Focal anastomosing of the proliferative ducts was identified. In few dilated ducts, the epithelial lining was composed of an inner layer of columnar cells with well-formed apical cilia and intracytoplasmic mucin and an outer layer of myoepithelial cells. The mucinous and ciliated cells were positive for epithelial membranous antigen and carcinoembryonic antigen, but negative for estrogen receptors, progesterone receptors, and thyroid transcription factor-1. Because this variant of eccrine metaplasia has not hitherto been reported in the literature, the term ciliated and mucinous adenomatous syringometaplasia was proposed for this unusual histologic finding. Mucinous and ciliated adenomatous syringometaplasia not only expands the spectrum of metaplastic changes in sweat gland units, but also might represent the missing link in the histogenesis of a subset of cutaneous ciliated cysts.

Cutaneous acantholytic dyskeratotic acanthoma accompanying syringofibroadenomatous hyperplasia with proliferation of mature sebocytes: A case report

Acantholytic dyskeratotic acanthoma is a rare variant of epidermal acanthoma. It has a flat, plaque-like structure and is characterized microscopically by acantholysis and dyskeratosis. Eccrine syringofibroadenomatous hyperplasia is benign and likely reactive. It has recently been considered as a hyperplastic process affecting the eccrine ducts rather than the neoplasm because of its pathological heterogeneity and wide clinical associations. In this article, we present the case of 97-year-old Japanese women with a 10-mm wide, painful acantholytic dyskeratotic acanthoma accompanied by syringofibroadenomatous hyperplasia in the right femoral region. Although syringofibroadenomatous hyperplasia is known to occur as a reactive process with various dermatoses and cutaneous tumors, to date, there have been no reports of cases of acantholytic dyskeratotic acanthoma accompanying syringofibroadenomatous hyperplasia. Moreover, this case also includes the unusual finding of an increase in the mature sebocytes in the area of the syringofibroadenomatous hyperplasia.

Primary cutaneous solitary fibrous tumor with entrapped eccrine components

First described in the pleura, solitary fibrous tumor (SFT) was subsequently reported in a variety of organ systems. Compared to other anatomic sites, primary cutaneous and superficial SFTs are relatively rare. Although several histopathologic variants of cutaneous and superficial SFT have been described, a primary cutaneous SFT harboring glandular components has not hitherto been documented in the literature. The current case report describes a spindle cell neoplasm of the right finger in a female patient with characteristic morphologic and immunohistochemical features of a SFT. Unexpectedly, various glandular and ductal components were identified in the SFT. A few hyperplastic lobules of sweat glands demonstrating similar morphology as the intratumoral glandular components and composed of secretory coils displaying mucinous metaplasia and ducts were detected in the attached subcutaneous tissue, suggestive of an inductive or obstructive effect of the SFT on the eccrine units. The intratumoral glands and ducts were judged to represent entrapped benign eccrine components from the attached subcutaneous tissue. Since this variant of SFT with entrapped eccrine components could mimic many biphasic epithelial and stromal tumors, pathologists should be aware of this unusual variant of SFT to avoid potential erroneous diagnosis, particularly mistaken confusion with a biphasic synovial sarcoma.

Chronic Venous Insufficiency as a Predisposing Factor for Basal Cell Carcinoma on Legs

BACKGROUND

The main risk factor associated with basal cell carcinomas (BCCs) is believed to be exposure to ultraviolet radiation (UVR). In the case of lower limb BCC, the frequency is higher in women, possibly because of greater exposure of the leg to UVR. Chronic venous insufficiency (CVI), also more common in women, may have some association with leg BCCs.

METHODS

We retrospectively evaluated the histopathological features of leg BCCs removed between 1993 and 2017 in a tertiary referral center. The patients' clinical data were obtained from medical records, considering, in particular, CVI.

RESULTS

We selected 149 patients with leg BCCs, predominately occurring in elderly Caucasian women. Of those, 71 had a clinical diagnosis of CVI in whom the clinical tumor size and frequency of recurrences were significantly higher than patients without CVI. There was an association between clinical diagnosis of CVI and histological findings of (1) follicular induction in epidermis and (2) distal sweat duct hyperplasia.

CONCLUSIONS

CVI, besides the already known UVR exposure, is probably associated with leg BCCs and may determine a worse BCC course.

Dermatopathology of Cutaneous Cystic Lesions: A Practical Review With Diagnostic Clues and Pitfalls

BACKGROUND

Cystic lesions are common in the daily practice of dermatologists and dermatopathologists, and in most cases, a straightforward diagnosis can be done. Yet, some variants and situations may cause diagnostic problems or carry prognostic and/or systemic implications.

OBJECTIVE

To review the histopathological features of the most frequent cystic lesions, either true cysts or pseudocysts, and provide some clues and pitfalls to bear in mind for troublesome situations such as solid-cystic tumors; uncommon variants; incidental findings; artifactual, reactive, or infectious cavities; cysts as a warning of systemic and hereditary diseases; and malignant cystic tumors, either primary or metastatic.

METHODS

The histopathological diagnostic criteria of most cystic lesions and their potential caveats will be discussed, offering some diagnostic clues.

RESULTS

Cystic lesions of the skin can primarily be classified into true cysts and pseudocysts. The most frequent pseudocysts are sinus pilonidalis and mucin-filled cavities. True cysts can be divided according to their epithelial origin or differentiation into epidermal/pilar cysts, cysts from glandular appendages, and from embryonic remnants. Diagnostic dilemmas and possible pitfalls in cystic lesions are reviewed, offering some keys to solve them.

CONCLUSIONS

Knowledge of the histopathology of cystic lesions contributes to their correct diagnosis, improving the management of patients.

Follicular induction and CK20+ Merkel cells overlying cutaneous focal mucinosis

BACKGROUND

Cutaneous focal mucinosis (CFM) or focal dermal mucinosis is a benign reactive process categorized as a primary mucinosis. Skin biopsy is essential for diagnosis, as the clinical appearance is often non-specific. Follicular induction is a phenomenon whereby the epidermis is induced by an underlying process to form primitive or mature hair follicles, and is commonly seen overlying dermatofibromas. Follicular induction has been rarely described in CFM.

METHODS

We performed a retrospective histological review of lesions of CFM confirmed by skin biopsy from 2010 to 2015 in our department.

RESULTS

We found that 11% (11/98) of CFM lesions showed follicular induction. Cytokeratin 20 (CK20) immunostaining was performed on all 11 of these biopsies that showed follicular induction and highlighted an increased density of CK20+ Merkel cells within the basaloid epidermal proliferations.

CONCLUSION

As superficial basal cell carcinomas (BCC) often show a mucinous stroma around the basaloid islands, CFM with follicular induction may closely mimic a BCC histologically, particularly in superficial shave biopsies. Therefore, it is important that dermatopathologists be aware of this phenomenon. Furthermore, CK20+ staining within the basaloid epithelial proliferations may be helpful in differentiating CFM with follicular induction from a BCC.

Syringometaplasia: variants and underlying mechanisms

Syringometaplasia is an adaptive, benign, metaplastic cellular process that affects the eccrine ducts and glands in response to a variety of physiological or pathological stimuli. Different subtypes of syringometaplasia have been described, including the squamous, mucinous, and adenomatous types. These metaplastic changes have been reported in association with chemotherapeutic agents, as well as with a variety of skin disorders including multiple infectious, neoplastic, and inflammatory skin diseases. In this review, we attempt to shed light on the different patterns of syringometaplasia, its pathogenesis, the plethora of skin conditions in which it may be observed, and the differential diagnoses that should be considered.

Oral plexiform schwannoma with unusual epithelial induction

Rare epithelial structures in benign nerve sheath tumors are almost always glandular in appearance. We describe a case of intraoral plexiform schwannoma with concurrent squamous epithelial hyperplasia. The lesion occurred as a pigmented nodule on the gingiva of a 35-year-old woman with no systemic involvement. Histologically, unencapsulated, plexiform fascicular proliferations of schwann cells could be traced from the submucosa to the lamina propria, finally making direct contact with heavily pigmented, elongated rete ridges of the overlying epithelium. Also noted was a schwannian network centered on clustered odontogenic epithelial rests of mature squamous-type, the number and size of which had markedly increased. Impressive immunoprofiles of periepithelial neural microfascicles included the complete absence of axon and perineurium and the unexpected presence of endoneurial fibroblasts. The repertoire of epithelial changes was in a confined area with no extension beyond, supporting hyperplasia induction by an underlying/surrounding schwannoma.

Primitive follicular induction in molluscum contagiosum

BACKGROUND

Molluscum contagiosum (MC) is the commonest human poxvirus infection. Follicular induction has rarely been observed in the epidermis surrounding lesions of MC. A virus-induced localized proliferation of germinative/stem cells of the folliculosebaceous-apocrine unit has been suggested as the underlying cause, however few reports of this peculiar phenomenon exist in the literature and the mechanisms involved in this proliferation require further study.

METHODS

We prospectively collected MC cases showing multifocal areas of primitive follicular induction involving the adjacent undersurface epidermis. Immunohistochemical expression of BerEP4, PHLDA1 and cytokeratin 20 (CK20) was evaluated in the basaloid germs surrounding the lesions. For PHLDA1, we used epidermal melanocytes as a positive internal control. For BerEP4, we employed a basal cell carcinoma (BCC) and for CK20, colon as positive external controls. An incubation without the primary antibody functioned as an external negative control.

RESULTS

All the cases studied showed an intense positive staining of the basaloid buds with BerEP4 and weaker stain for PHLDA1. CK20 showed the presence of scattered Merkel cells within the induced epidermal basaloid proliferations favoring their reactive origin.

DISCUSSION

The pathogenetic mechanisms behind the development of these microscopic features and the link between follicular induction and poxvirus infection are explored. Awareness of this unusual phenomenon by dermatopathologists will be helpful in avoiding a misdiagnosis of a superficial BCC in such cases.

CONCLUSIONS

BerEP4 and PHLDA1 were consistently expressed in the areas of primitive follicular induction surrounding lesions of MC. CK 20 stained the Merkel cells present in the basaloid buds. All these findings support the reactive origin of this phenomenon, which we believe is most probably viral-induced.

Scar and induction of follicles: an association worthy of greater awareness

Alterations in the dermal connective tissue can sometimes induce epidermal changes with adnexal differentiation. Typically associated with dermatofibromas, such changes can also be seen in a wide range of reactive and neoplastic conditions. Scar is sometimes listed as an underlying cause of follicular induction, but this association seems to be poorly recognized and not widely discussed in the literature. In this article, the authors illustrate the spectrum of follicular induction, which may be associated with a dermal scar emphasizing on patterns, which can be mistaken for a basal cell carcinoma.

Follicular induction overlying a dermatofibrosarcoma protuberans

The term "induction" has been used to describe epidermal changes overlying a dermatofibroma (DF). Follicular induction is most often associated with DF, but can be observed in other lesions, including focal mucinosis, nevus sebaceous, seborrheic keratosis, wart, neurofibroma, and scars. Dermatofibrosarcoma protuberans (DFSP) is a malignant fibrohistiocytic tumor that may be difficult to distinguish from DF. In contrast to DF, the epidermis overlying DFSP is usually attenuated or ulcerated. Here, we report a case of DFSP exhibiting follicular induction of the overlying epidermis. This epidermal change has been rarely reported in DFSP and may present a diagnostic pitfall in superficially sampled lesions.

Cutaneous changes in fibrous hamartoma of infancy

Only a few published case of fibrous hamartoma of infancy (FHI) have commented on the changes in the overlying skin. There are descriptions of individual cases with cutaneous hyperpigmentation, hypertrichosis and hyperhidrosis. It is interesting to describe our case because, to our knowledge, the altered pigmentation of the overlying skin, with hairs on the surface, and eccrine gland hyperplasia combined with abortive hair follicles has not been reported together in association with the FHI. We recommend that all the biopsies must be excisional including overlying skin, thus the epidermal and dermal adnexal changes can be assessed in the microscopic evaluation which could have relevant implications from clinical and embryological point of view.

Follicular induction in a case of molluscum contagiosum: possible link with secondary anetoderma-like changes?

Molluscum contagiosum (MC) can rarely show follicular neogenesis as a result of proliferation of virus-infected basal cells. We report a case of molluscum contagiosum showing multifocal areas of primitive follicular induction involving the adjacent surface epidermis. The underlying dermis showed histological features suggestive of secondary anetoderma. The pathogenetic mechanisms behind development of these microscopic features and the putative link between follicular induction and secondary anetoderma are explored. Awareness of this unusual phenomenon will be helpful in avoiding a misdiagnosis of a superficial basal cell (trichoblastic) carcinoma in such cases.

Folliculocystic and collagen hamartoma of tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by tumors and hamartomas in several organs including the skin.

OBJECTIVE

We sought to describe a new type of complex hamartoma in patients with TSC.

METHODS

This was a retrospective clinical and histopathologic evaluation of 6 cases.

RESULTS

The skin lesions consisted of large, painless, infiltrated plaques that were first noticed at birth or during early infancy on the abdomen, thigh, back, or scalp. In time, the plaques became studded with numerous follicular comedo-like openings and cysts containing and draining a keratinous or purulent material. The main histopathologic features were: abundant collagen deposition in the dermis and extending into the underlying fat; concentric, perifollicular fibrosis surrounding hair follicles; and comedones and keratin-containing cysts lined by infundibular epithelium, some of which were ruptured with secondary granulomatous reaction. Five of the 6 patients had a clinical diagnosis of TSC.

LIMITATIONS

Genetic testing was performed in only one patient.

CONCLUSION

This distinctive folliculocystic and collagen hamartoma has not been recognized previously in association with TSC.

Morphometric analyses of elastic tissue fibers in dermatofibroma: clues to etiopathogenesis?

BACKGROUND

The etiopathogenesis of dermatofibroma (DF), a common benign fibrohistiocytic tumor, is debatable. The goal of this study was to ascertain the density of elastic tissue fibers in DF in an effort to investigate whether this provides an insight into its etiopathogenesis.

METHOD

Three groups comprising eight cellular DFs, eight paucicellular DFs and eight scars (control group) were stained with a modified Verhoeffs-van Gieson (without counterstain), and elastic fibers in three randomly selected fields within the lesional area/case semiquantitatively analyzed and examined in a blinded fashion.

RESULT

The mean density of elastic tissue fibers in cellular DF was 6.81 (1.38-15.89); in paucicellular DF, 2.46 (0.14-5.79) and in scar, 2.95 (0.97-10.69). Overall, significant differences in density of elastic tissue fibers were observed only between cellular DF and the other two groups (vs. paucicellular variant, p = 0.03 and vs. scar, p = 0.05). Morphological changes observed included thickness, clumping, elongation and waviness (cellular DF) and margination of elastic tissue fibers (paucicellular variant).

CONCLUSION

While the jury still appears to be out regarding the etiopathogenesis of DF, the reduction in density of elastic tissue fibers in the paucicellular variant compared with its cellular counterpart lends credence to the concept of evolutionary stages of DF.

Cutaneous focal mucinosis causing follicular induction of the epidermis

Cutaneous focal mucinosis has been rarely reported in association with follicular induction of the epidermis. We present 2 cases of focal mucinosis with follicular induction and describe the histopathologic findings to create awareness of this association and to prevent confusion with other diagnoses such as dermatofibroma with follicular induction or superficial basal cell carcinoma.

Trichoadenoma Associated With an Intradermal Melanocytic Nevus: A Combined Malformation

Melanocytic nevi have been associated with epidermal hyperplasia, adnexal hyperplasia with follicular and sebaceous differentiation, cysts, and tumors of epidermal or adnexal origin. We report a combined cutaneous hamartoma in a 29-year-old woman that comprised a trichoadenoma within an intradermal melanocytic nevus. Clinical diagnosis was a malignant transformation of a melanocytic nevus. Histopathologically, multiple keratinous cysts together with solid islands or masses of eosinophilic epithelial cells were closely intermingled with the nevus cells. Occasional nests of basaloid cells were present. Although to our knowledge this association has not been previously reported, it is worth considering that trichoadenoma and desmoplastic trichoepithelioma are the two ends of a spectrum of lesions. This combined hamartoma reported herein is important because growth of these lesions could be clinically misinterpreted as malignant transformation of a preexisting lesion. Histologic study will reveal the correct diagnosis in such cases.

Cutaneous changes in fibrous hamartoma of infancy

BACKGROUND

Fibrous hamartoma of infancy (FHI) is a fast growing soft tissue tumor that usually arises in the first 2 years of life. The histology of the lesion has been well described. Few studies, however, have looked at changes in the overlying skin and its appendages.

METHODS

A database search performed at British Columbia Children's Hospital yielded 15 cases of unequivocal FHI occurring in 12 patients (three were recurrences). Of these, we were able to retrieve 13. Five of 13 cases had sections including epidermis. These slides were reviewed with specific emphasis on skin adnexae.

RESULTS

Of the cases with excised epidermis in continuity with the lesion, 5/5 had eccrine changes, including hyperplasia, duct dilatation, intraluminal papillary formations, and squamous syringometaplasia. One case showed epidermal basaloid follicular hyperplasia.

CONCLUSIONS

This study shows that eccrine changes are frequently seen in cases of FHI when overlying skin is sampled. This may be a useful clue to consider this diagnosis, especially when the biopsy is superficial.

Trichoblastic Infundibular Cyst

We report 4 cases of an infundibular cyst that histopathologically showed small papillary projections of follicular germinative cells emanating from the basal layer of the cyst wall. Some of these projections branched and formed a reticulated pattern. This cystic lesion is histopathologically distinctive. We propose to designate it as a trichoblastic infundibular cyst because its lining resembles that of an infundibular cyst, yet it has cells that resemble those of the follicular germ in its wall.

[Basal cell carcinoma overlying a dermatofibroma]

The epidermis over a dermatofibroma may show changes that range from simple hyperplasia to the proliferation of basaloid cells, which can become morphologically indistinguishable from basal cell carcinoma. The existence of a true basal cell carcinoma overlying a dermatofibroma is infrequent. These basaloid proliferations have usually been considered to be the result of the inductive effect of the fibrohistiocytic proliferation of the dermatofibroma on the epithelial cells of the hair follicle; therefore, it would be a reactive phenomenon and not truly neoplastic. We describe a case of dermatofibroma that presented with a basaloid proliferation identical in appearance to a basal cell carcinoma on the overlying epidermis.

Clinical, dermoscopy and histological correlation study of melanotic pigmentations in excision scars of melanocytic tumours

BACKGROUND

Melanotic pigmentations in scars consecutive to the excision of melanocytic tumours can be secondary to a reactive phenomenon related to the scar tissue or to a recurrence of the melanocytic lesion excised in the first case. Recurrent naevi may sometimes adopt unusual features that make them difficult to differentiate from a melanoma.

OBJECTIVES

To describe the clinical, dermoscopic and histological features of melanotic pigmentations in scars consecutive to the excision of melanocytic tumours, and to correlate the histological diagnosis with the dermoscopic features.

METHODS

This was a prospective cohort study using macrophotography, dermoscopy and histopathological study. Ninety-five melanotic pigmentations (77 patients) in scars secondary to the excision of melanocytic tumours were prospectively collected in the Department of Dermatology at the Instituto Valenciano de Oncología in Valencia, Spain. Histopathological study was performed in 57 scars.

RESULTS

Thirteen dermoscopic structures were identified. Four criteria allowed a differentiation between reactive and specific melanocytic pigmentations. Presence of globules and presence of heterogeneous pigmentation were features associated with specific melanocytic pigmentations (P < 0.0001). Presence of a regular network and presence of streaks were more frequently found in reactive pigmentations (P = 0.023 and 0.026, respectively).

CONCLUSIONS

Dermoscopic examination of melanotic pigmentations in excision scars of melanocytic tumours provides useful information about the origin of that pigmentation. Based on such information, recurrent naevi can be differentiated from reactive pigmentations in most cases. Excision and histopathological diagnosis continue to be imperative in some cases of recurrent naevi with atypical clinical features.

Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type I, but not sporadic neurofibromas: a study of 226 cases

BACKGROUND

Neurofibromatosis, type 1, is associated with cutaneous melanin pigmentation, but an association with ordinary melanocytic nevi has not been described.

METHODS

This retrospective case-control study was designed to see if neurofibromas in patients with neurofibromatosis, type 1 (NF-1) differ from sporadic neurofibromas (SN) in their incidence of associated melanocytic nevi and other histologic features. Slides from 114 NF-1 were compared with 112 SN and 300 intradermal melanocytic nevi (IDN).

RESULTS

Small lentiginous melanocytic nevi were identified over 13 NF-1 (11%) but no SN (P=0.0002). Compared with other NF-1, NF-1 with nevi were more frequently associated with melanocytic hyperplasia, giant melanosomes and diffuse neurofibroma (P<0.03). Compared with SN, NF-1 were also more frequently associated with melanocytic hyperplasia, lentigo simplex-like changes, diffuse neurofibroma and plexiform neurofibroma (P<0.001). Sebaceous hyperplasia (14%), dermal elastosis (9%), lipomatous change (8%), epithelial cysts (4%) and keratin granulomas or folliculitis (3%) were not significantly different in prevalence between NF-1, SN and the control group of IDN.

CONCLUSIONS

This study suggests that there is a difference in the potential for melanocytic proliferation in NF-1 compared with SN. NF-1, SN and IDN are associated with a similar range of incidental histologic changes. Ball NJ, Kho GT. Melanocytic nevi are associated with neurofibromas in neurofibromatosis, type 1, but not sporadic neurofibromas. A study of 226 cases.

Reactive Syringofibroadenomatous Hyperplasia in Peristomal Skin with Formation of Hybrid Epidermal-Colonic Mucosa Glandular Structures, Intraepidermal Areas of Sebaceous Differentiation, Induction of Hair Follicles, and Features of Human Papillomavirus Infection

We report a case of reactive syringofibroadenomatous hyperplasia in peristomal skin. The patient was a 62-year-old woman who had undergone abdominoperineal resection of the rectum for rectal adenocarcinoma with subsequent colostomy 2 years earlier. Clinically, a nodule and small, whitish, warty lesions developed at the outer margin of the stoma extending onto the adjacent skin. Following a clinical suspicion of adenocarcinoma, recurrent at the colostomy site, a 5 x 4 x 3-cm excision of the peristomal skin and the affected portion of the stoma was performed and submitted for histologic examination. The biopsy revealed a peculiar composite lesion of reactive syringofibroadenomatous hyperplasia and the excised part of the stoma. Several unusual histopathological features were detected in the syringofibroadenomatous part of the lesion such as the formation of plentiful hybrid epidermal-colonic mucosa glandular structures, intraepidermal areas of sebaceous differentiation, koilocytic changes, induction of rudimentary hair follicles, and intradermal mucinous lakes. The cellular composition of the glandular structures was mainly similar to that seen in a normal colonic mucosa epithelium. They also contained occasional Paneth cells. Being located at a distance from the stoma, these accentuated colonic mucosa epithelial glands reaching the epidermis may be a diagnostic pitfall prompting the consideration of adenocarcinoma involving the stoma. The rudimentary follicles and sebaceous differentiation were probably induced by an altered stroma and/or human papillomavirus (HPV): HPV, type 36 was identified by PCR using consensus primers followed by sequencing of the PCR products.

Dermatofibroma: Upregulation of Syndecan-1 Expression in Mesenchymal Tissue

Cell surface proteoglycans play a prominent role in tissue remodeling and homeostasis. Syndecans, their most prominent members, act by binding to growth factors and interstitial matrix molecules. They, thereby, modulate the effect of the primary ligand-receptor interaction at the cell membrane by increasing the affinity of cell-ligand interactions. Additionally, they influence the strength of cell-cell and cell-matrix interactions. Syndecan-1 is the prototypical member of this family of proteins. Under physiological conditions, its expression is restricted to the epidermis, the outer root sheath of the anagen hair follicle, and the sweat gland epithelium. The dermal compartment-with the exception of the follicular papilla of the anagen hair follicle-physiologically does not express syndecan-1. Dermatofibromas are mesenchymal lesions, which often exhibit hyperplastic changes in the overlying epidermis. In analogy to the hair follicle, they, thereby, can be used as a model for studying epithelial-mesenchymal interactions. In the current study, we examined dermatofibromas immunohistochemically for syndecan-1 expression. We report immunoreactivity for syndecan-1 in dermatofibromas, which correlates mainly with the deposition of intercellular matrix material. Syndecan-1 is also noted in the stroma surrounding areas of basaloid hyperplasia overlying dermatofibromas and may be important in the pathogenesis of this inductive phenomenon. In analogy to the follicular papilla of the anagen hair follicle, the staining pattern for syndecan-1 in dermatofibromas indicates that this cell surface protein is produced by stromal cells and most likely serves an essential function in the growth of these common mesenchymal cutaneous lesions.

Dilated pore: a case report and an immunohistochemical study of cytokeratin expression

We report a 71-year-old Japanese female with a dilated pore in the form of a nodule above her right eyebrow. Histologic examination revealed a flask-shaped, keratinous cystic structure that was continuous with the surface epidermis and had numerous elongated rete ridges in the lower portion. An immunohistochemical study using a panel of monoclonal antibodies against cytokeratins (CKs) and involucrin detected CK1 and CK10 in the suprabasal cells of the cystic structure. CK8 and CK19 expression was observed in the outermost layer of some elongated rete ridges; it was composed of pallisading columnar cells. Most parts of the outermost layer of the cystic structure stained positively with AE1 antibody. From these immunohistochemical findings, we speculated that the dilated pore in our case was an isolated clinical entity is a follicular tumor differentiating mainly toward the infundibulum and partly toward the isthmus.

Possible mechanisms of hypopigmentation in lichen sclerosus

Lichen sclerosus (LS) shares with vitiligo a milky-white appearance. By biopsy, pathognomonic dermal sclerosis readily distinguishes LS from vitiligo and other causes of leukoderma. To determine what the mechanism of hypopigmentation is in LS, we examined samples from LS cases for alterations in melanin content (Fontana-Masson stain) and melanocyte number (HMB-45 [PMEL-17/gp100], Mel-5 [TRP-1], Mart-1 [Melan A]) and compared these findings with those in controls of normal skin, acute scars, vitiligo, and lichen planus (LP; a common inflammatory cause of hyperpigmentation). The degree and extent of melanization found in LS overlapped with that in acute scars showing predominantly hypomelanized keratinocytes, with that in LP containing regions with numerous melanophages, and with that in vitiligo exhibiting focal regions of keratinocytes devoid of melanin pigment. By hematoxylin-eosin staining and immunocytochemistry for Mel-5 and Mart-1, LS had a lower mean count of melanocytes than acute scars, LP, and normal skin per 200 basal keratinocytes. In addition, a few LS cases had a significant loss of melanocytes comparable to that of vitiligo. Surprisingly, Mart-1 identified rare melanocytes in 67% of vitiligo cases and a significantly larger pool of melanocytes in LS and controls other than those labeled by Mel-5. Furthermore, LP and evolving lesions of LS contained the highest Mart-1 counts. HMB-45-immunoreactive melanocytes were found in the majority of acute scars and in LP and late-stage LS lesions at significantly lower levels than Mel-5- and Mart-1- labeled melanocytes, but they were not found in vitiligo or normal skin. We propose that several mechanisms may play a role in the production of leucoderma in LS: 1) decreased melanin production; 2) block in transfer of melanosomes to keratinocytes; and 3) melanocyte loss. The latter finding may be the pathogenic connection (lichenoid dermatitis of LS triggering an autoimmune reaction to melanocytes) that underlies the documented association of LS with vitiligo.

Fibroepithelioma-like changes occurring in perianal Paget's disease with rectal mucinous carcinoma: case report and review of 49 cases of extramammary Paget's disease

BACKGROUND

Anogenital Paget's disease (PD) may be accompanied by varying degrees of epidermal hyperplasia. The histological changes can be reminiscent of fibroepithelioma of Pinkus.

METHODS

We present a case of perianal PD associated with fibroepitheliomatous epidermal hyperplasia in a 76-year-old-man with an underlying rectal mucinous carcinoma. We also carried out a retrospective analysis of 51 biopsies from 49 cases of extramammary PD to see whether particular epidermal changes occur in association with PD in different anatomic locations.

RESULTS

A tumor, 3 cm in diameter, was noted in the patient's perianal skin. Histologically, it was composed of anastomosing thin epithelial strands with follicular differentiation. Paget's cells were distributed in the epithelial strands of this tumor as well as in the surrounding epidermis and anal epithelia. In our series of extramammary PD, epidermis was hyperplastic in two of two perianal cases, 26 of 43 genital skin samples, and one of six axillary PD biopsies. The stroma beneath the hyperplastic epidermis tended to be rich in thin collagen fibers and fibroblasts.

CONCLUSIONS

Anogenital PD was more frequently associated with epidermal hyperplasia than axillary PD. Fibroepitheliomatous hyperplasia may be induced by the altered stroma associated with PD.

Winer's dilated pore: the infundibuloma

This article summarizes Louis H. Winer's description of the dilated pore and some of the pertinent literature about the dilated pore. To better understand the discussion that follows, there is a brief review of the histology of the follicular infundibulum and isthmus, then a discussion of the architectural and cytologic differentiation of proliferations that reputedly differentiate toward the infundibulum. These other proliferations with their original photomicrographs are discussed rather extensively to support the argument that they do not differentiate either architecturally or cellularly toward the infundibulum. I then present evidence that contradicts those authors who claim that Winer's dilated pore is only a cyst and conclude that it is a neoplasm sui generis and the only neoplasm of the skin that differentiates architecturally and cytologically towards the infundibulum (the infundibuloma).

An unusual melanocytic lesion associated with eccrine duct fibroadenomatosis and syringoid features

The intimate association of nevomelanocytic nevi with eccrine ducts commonly seen in congenital nevi was emphasized by Mishima, who described as eccrine-centered nevi those lesions characterized by nevomelanocytic cells predominantly proliferating around and within the eccrine sweat duct walls. However, there were no changes in the overlying epidermis, dermis, or eccrine acrosyringeal or dermal duct proliferation in these lesions. We present the case of a 16-year-old boy with a 1-year-history of a 0.6-cm diameter single tan papule on the right heel, clinically thought to be a Spitz nevus. Histopathologic examination revealed a compound nevomelanocytic nevus associated with epidermal hyperplasia, thin anastomosing cords of acrosyringeal epithelium extending within the dermis, and eccrine ductal proliferation in a syringoma-like pattern associated with a dense fibrous stroma. Features that distinguish our case from eccrine-centered nevus are that the latter lacks epidermal and eccrine duct hyperplasia and a dense fibrous stroma. The location of the lesion on the heel in our case suggests the possibility that the pathologic changes observed could result from repetitive trauma.

Proliferation of eccrine sweat ducts associated with heterotopic neural tissue (nasal glioma)

The term "nasal glioma" refers to the presence of heterotopic neural tissue, mainly glial in nature, at or near the root of the nose. We describe a case in which all three components of neural tissue, that is, leptomeninges, glia, and neurons, were present, associated with sweat-duct hyperplasia. Proliferation of sweat ducts is a reactive process in some benign and malignant neoplasms, hamartomas, and cysts. This is the first documented case of hyperplasia of eccrine ductal epithelium induced by nasal glioma.

Trichoblastoma is the most common neoplasm developed in nevus sebaceus of Jadassohn: a clinicopathologic study of a series of 155 cases

Nevus sebaceus of Jadassohn is a hamartoma that combines epidermal, follicular, sebaceous, and apocrine gland abnormalities. Classically, several types of cutaneous neoplasms have been associated with this hamartoma, with basal cell carcinoma being the most frequently described malignancy. We studied a series of 155 examples of nevus sebaceus of Jadassohn with clinicopathologic correlation. Several histopathologic changes related to the age of the patients were found. In our series, we could not identify any cases of authentic basal cell carcinoma. In contrast, several examples of primitive follicular induction and of trichoblastomas were seen. Other cutaneous hamartomas, hyperplasias, and neoplasms found in our series of nevus sebaceus of Jadassohn included syringocystadenoma papilliferum, sebomatricoma, apocrine gland cyst, poroma, different histopathologic variants of warts (classic warts, tricholemmoma, and desmoplastic tricholemmoma), primitive follicular induction, and ductal induction. In our series, no examples of malignant neoplasms were identified. On the basis of these findings, the classically recommended treatment for this hamartoma, which consists of early excision to prevent the development of malignancy, seems to be inappropriate.

A poroid neoplasia arising close to a seborrheic keratosis and a trichoepithelioma

A 69-year-old woman had a well-defined, slightly raised, brownish, keratotic plaque with an eccentric group of roughly circular, bluish, dome nodules on her right scapular area. Histological study revealed the presence of an eccrine poroma demonstrating features of eccrine poroma, hidroacanthoma simplex, and dermal duct tumor and arising in a lesion of seborrheic keratosis and a trichoepithelioma. In the eccrine poroma region, an area with malignant changes was evident. The findings in this case support the view of eccrine poroma as a spectrum of histological variants and the possibility of malignant transformation from a eccrine poroma towards porocarcinoma. The association with seborrheic keratosis is most probably coincidental, and the trichoepithelioma was probably due to induction of the tumoral stroma on adjacent follicular epithelia.