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Discrete junctional cellular aggregates ("nests"), partially staining with melanocytic markers, are described in lichenoid tissue reaction, mainly from chronically sun-exposed skin. The concomitant epidermal flattening and papillary dermal fibrosis with melanophages, may raise the differential diagnosis to that of a regressing melanoma. We describe three cases of interface dermatitis of the head/neck area with clinicopathological features of melanotic discoid lupus erythematosus. These cases showed junctional aggregates, a few composed of inflammatory cells and colloid bodies ("pseudomelanocytic nests"), while others composed of S100- but MART-1+, MITF+, and SOX-10+ cells ("true melanocytic nests"); negativity of the melanocytic component for PRAME was a clue to benignity. True junctional melanocytic nesting may be induced by lichenoid dermatoses on chronically sun-damaged skin. The presence of colloid bodies and of the double negativity for S100 (within nests) and PRAME (both within nests and single melanocytes), together with clinicopathological correlation, avoids misdiagnosis.

In recent years the increased number of scalp biopsies in alopecia has afforded the dermatopathologist improved confidence in distinguishing the histopathologic characteristics of ‘classic’ scarring and non-scarring alopecias, as well as the spectrum of their presentation. Occasionally, however, histopathologic ‘dogmas’ have been disproven. The loss of sebaceous glands considered to be a clue to scarring alopecia or the peribulbar lymphoid cell infiltrate diagnostic of alopecia areata may present in unconventional scenarios, and thus, represent pitfalls. Clues to diagnose histopathologically ‘silent’ (invisible) alopecias, the identification of multiple etiologies, and awareness of the ‘time-factor’ are herein discussed.

Deriving from the Greek word λeιχήν for "tree moss" and the Latin word planus for "planar," lichen planus is a relatively uncommon and heterogeneous cutaneous disorder that typically develops in middle-aged adults. Despite the significant clinical burden associated with the disorder, little well-conducted molecular research has been undertaken, possibly because of heterogeneity impeding consistent and confident phenotyping. The multiple variants of lichenoid disease bear overlapping clinical and pathologic features despite manifesting as distinct clinical disorders. The first article in this 2-part continuing medical education series provides a comprehensive overview of the clinical and pathologic characteristics of cutaneous lichenoid dermatoses and links these manifestations to recent advances in our understanding of the underlying pathobiology of such diseases.

Cronkhite-Canada syndrome is an acquired inflammatory polyposis syndrome in which alopecia, onychomadesis and hyperpigmentation occur concurrently with gastrointestinal symptoms. The pathophysiology of alopecia in Cronkhite-Canada syndrome has not been definitively elucidated. We present evidence for alopecia areata incognita as a possible mechanism of hair loss.

Background Anagen effluvium with reversible scalp alopecia is a known side effect of chemotherapy. However, there are an increasing number of reports in the literature documenting permanent alopecia in patients treated with taxanes. Objective We sought to describe the clinicopathologic features in breast cancer patients who underwent treatment with taxanes and adjuvant hormonal chemotherapy. Methods We reviewed the clinical and histopathologic information of a cohort of 10 patients treated with taxanes and adjuvant hormonal chemotherapy. Results We have observed 3 types of clinical patterns of alopecia (types A, B, and C), and have validated the histopathologic features showing alopecia areata–like and female pattern hair loss. Limitations The study was based on a small sample size and retrospective retrieval of clinical information and histopathologic review of posttreatment slides. Conclusions We hypothesize a clinicopathologic model of hair follicle cycle disruption in response to the chemoinflammatory and hormonal insults to the hair follicles resulting in permanent alopecia. Clinicopathologic correlation is paramount to the understanding of the morphobiologic pathways in chemotherapy-induced alopecia caused by taxanes and adjuvant hormonal treatment.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. Mycosis fungoides classically presents in the skin as patches, plaques, tumors, or erythroderma, progressing to involve the lymph nodes and peripheral blood. The many clinical variants, with different histologic patterns, and the subtle early clinical and histologic changes may delay early diagnosis and present a diagnostic challenge for clinicians. The greatest challenge in diagnosis is the pre-mycotic stage, which may closely resemble eczematous or psoriasiform dermatitis clinically and histologically. The persistence of lesions and inadequate response to treatment are the first warning signs. Later stages of MF have a poor prognosis with poor therapeutic response and fatal outcome. We describe a 72-year-old man, who presented with a two-year history of an unusual eruption, which started on the abdomen, around the waistline, and gradually spread to involve his back, trunk, and buttocks. Clinically, the skin eruption presented as tiger-like stripes. The diagnosis was confirmed after histopathologic examination. The patient was treated with NB-UVB phototherapy with marked improvement.

Background We compared the use of an immunohistochemical (IHC) method using a monoclonal antibody to BRAF V600E (which detects the main BRAF mutation) with existing DNA probe screening in tissue samples from 71 patients with malignant melanoma. Materials and methods Paraffin blocks were cut to provide consecutive slides for haematoxylin and eosin staining, and for known positive micro-array DNA control material. IHC was performed by the Optiview detection system. All slides were scored independently by the clinical lead and the laboratory lead using a positive/negative system. Results The DNA method found 26 samples to be positive, the IHC found 21 to be positive, giving a sensitivity value for IHC of 80.8%. However, all of the 45 samples found to be negative by DNA were also negative by IHC, giving a specificity of 100%. There were 66 instances of full agreement, giving a concordance of 93%. Together, these data give a kappa statistic of 0.843, indicating very good agreement. Conclusion The data reveal a very close link between the two methods, supporting the use of the V600E as a primary screen for BRAF mutations in malignant melanoma. Samples found to be negative by this method may be retested by the DNA probe method. IHC detection conserves patient DNA from tumour blocks as only one section is required to perform the assay. The V600E antibody method is considerably cheaper and faster than the DNA probe assay, with a turn-around time of 24-48 hours, enabling more rapid clinical management.

The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process.

Background Few histologic studies describe the histopathologic aspects of scleromyxedema. Objective We sought to describe the histopathologic and immunohistochemical features of scleromyxedema in a large series of patients. Methods We studied all the cases with scleromyxedema diagnosed between 2000 and 2014 at participating centers. Sections with hematoxylin-eosin and special stains were examined. Immunohistochemistry for CD3, CD4, CD8, CD20, CD68, and factor XIIIa was performed in 10 cases. Results A total of 44 skin biopsy specimens from 34 patients were reviewed. Two different histopathologic patterns were observed: the classic microscopic triad (dermal mucin deposition, fibroblast proliferation, fibrosis) was identified in 34 specimens, whereas an interstitial granuloma annulare–like pattern was found in 10 specimens. A superficial perivascular infiltrate with T lymphocytes was found in all specimens whereas an interstitial proliferation of CD68 + epithelioid cells was identified in the 10 specimens with an interstitial granuloma annulare–like pattern. Elastic fibers were largely lost, explaining the redundant folds of the disease. Limitations This was a retrospective study. Conclusions Scleromyxedema shows 2 histopathologic patterns, including the classic type with the microscopic triad of mucin, fibroblast proliferation and fibrosis, and an interstitial granuloma annulare–like pattern. Recognition of these histologic presentations expands the spectrum of scleromyxedema and highlights the difficulty in diagnosing this disabling condition in the absence of a clinicopathological correlation.

Woolly hair nevus is a mosaic disorder characterized by unruly, tightly curled hair in a circumscribed area of the scalp. This condition may be associated with epidermal nevi. We describe an 11-year-old boy who initially presented with multiple patches of woolly hair and with epidermal nevi on his left cheek and back. He had no nail, teeth, eye, or cardiac abnormalities. Analysis of plucked hairs from patches of woolly hair showed twisting of the hair shaft and an abnormal hair cuticle. Histopathology of a woolly hair patch showed diffuse hair follicle miniaturization with increased vellus hairs.

The term dysplastic nevus derives from Greek (dys = abnormal) and (plasis = growth) and was coined to describe a distinct entity harbouring, in its name, a potential harm to the host [1]. In 1992, the National Institutes of Health Consensus Conference proposed to replace the term with “nevus with architectural disorder with and without cytologic atypia” [2]. However, the old terminology continues to be widely used. By inserting dysplastic nevus as an intermediate melanocytic lesion within the histologic morphobiologic spectrum of benign versus malignant lesions, it was felt that a diagnostic “comfort zone” was provided where diagnostic uncertainty on behalf of the pathologist may, in turn, guarantee re-excision of the lesion by the clinician [3, 4].

A common debate among dermatopathologists is that prior knowledge of the clinical picture of melanocytic skin neoplasms may introduce a potential bias in the histopathologic examination. Histologic slides from 99 melanocytic skin neoplasms were circulated among 10 clinical dermatologists, all of them formally trained and board-certified dermatopathologists: 5 dermatopathologists had clinical images available after a 'blind' examination (Group 1); the other 5 had clinical images available before microscopic examination (Group 2). Data from the two groups were compared regarding 'consensus' (a diagnosis in agreement by ≥4 dermatopathologists/group), chance-corrected interobserver agreement (Fleiss' k) and level of diagnostic confidence (LDC: a 1-5 arbitrary scale indicating 'increasing reliability' of any given diagnosis). Compared with Group 1 dermatopathologists, Group 2 achieved a lower number of consensus (84 vs. 90) but a higher k value (0.74 vs. 0.69) and a greater mean LDC value (4.57 vs. 4.32). The same consensus was achieved by the two groups in 81/99 cases. Spitzoid neoplasms were most frequently controversial for both groups. The histopathologic interpretation of melanocytic neoplasms seems to be not biased by the knowledge of the clinical picture before histopathologic examination.

EMLA(®) (eutectic mixture of local anesthetics, 2.5% each of lidocaine and prilocaine in an oil and water emulsion) is used as a topical anesthetic. We report three cases of EMLA(®) -induced histopathologic changes on the vulvar epithelium. While there are some similar histopathologic features to those reported in extragenital skin, we describe additional findings on vulvar epithelium, which, to our knowledge, have not been reported previously. The patients presented with clinical signs suggestive of lichen sclerosus or erosive lichen planus (LP), but were all confirmed histopathologically as LP. The biopsy was taken after 15 min of EMLA(®) application and intradermal injection of 1% lidocaine. Blistering prior to intradermal lidocaine and the biopsy procedure was observed in two patients. The histopathologic changes observed in the epithelium included pallor of the upper epidermis, mild spongiosis, intraepidermal subcorneal and suprabasal acantholysis, congestion of the papillary dermal capillaries and extravasated erythrocytes. Basophilic granules were present, but rare, while the necrosis with multifocal clefting was more marked than in extragenital skin. It is important to be aware of these changes occurring on genital mucosa; these may occur in the absence of clinical signs and may obscure the primary underlying pathology, thus representing a diagnostic pitfall.

The histopathologic assessment of a scalp biopsy for alopecia relies largely on the quality of the specimen provided for evaluation. There are a number of different protocols in the literature which have been proposed over the years, but no consensus has yet been reached as to the appropriate number of biopsies to be taken, or to which sectioning technique is the gold standard for achieving the best diagnostic yield. We herein review the pros and cons of the various protocols and share the experience with our St John's protocol.

We were interested to read the article Frontal Fibrosing Alopecia - Possible Association with Leave-on Facial Skin Care Products and Sunscreens; A Questionnaire Study by Aldoori et al1. The authors sought to identify possible causative environmental factors associated with frontal fibrosing alopecia (FFA). One conclusion was that the use of facial products containing sunscreens might be implicated. This article is protected by copyright. All rights reserved.

Since it was first described by Kossard in 1994, frontal fibrosing alopecia (FFA) has been something of an enigma. The clinical heterogeneity of FFA, its apparent rarity, and investigators' suboptimal access to phenotypically consistent patient cohorts, may all have had a negative impact on delineating disease pathogenesis. Moreover, there is a relative paucity of epidemiologic interventional and basic research studies, and there have been no advances in translational therapeutics, unlike for other inflammatory dermatoses, such as alopecia areata (AA). Dermatologists anecdotally describe an increasing incidence in FFA over the last decade, which has led to the notion that the disorder may be induced by unknown environmental triggers. On the other hand, segregation of FFA in some families lends support to an unexplored genetic element implicated in disease pathogenesis. We herein review what is known about the pathobiology of FFA and formulate working hypotheses to advance insight into this intriguing hair disorder. This article is protected by copyright. All rights reserved.

Primary vulvar carcinoma is rare and thought to arise from either anogenital mammary-like glands or native apocrine sweat glands. The diagnosis is predominantly based on tumor morphology with supportive evidence from immunohistochemical staining and exclusion of a primary breast carcinoma. The primary modality of treatment is surgery, while optimal managment of advanced disease is unclear. We present the case of a lady who had metastatic recurrent apocrine carcinoma expressing estrogen receptors, who had a complete response assessed by PET-CT scanning after 7 months of tamoxifen therapy. The report includes a discussion of the histological diagnosis and assessment of response to treatment by PET-CT scanning.

Cutaneous areas previously affected by herpes viruses appear to become predisposed to the subsequent development of a range of other unrelated conditions. We describe here a case of discoid lupus erythematosus (DLE), possibly triggered by an episode of shingles that had occurred in the same area (ophthalmic branch of the left trigeminal nerve), a few weeks before.A Caucasian man in his early 70s presented with a three-week history of a persistent erythematous, crusty and focally excoriated eruption, [...]

Cutaneous collagenous vasculopathy is characterized by generalized cutaneous telangiectasia and unique microscopic and ultrastructural vascular changes, consisting of marked collagen deposition within the vascular walls of the post-capillary venules in the superficial dermis. There are only 4 previous cases described in the medical literature, all in males, mostly middle-aged. We have recently seen two female patients with clinical and histopathologic features diagnostic of cutaneous collagenous vasculopathy, indicating that it is not restricted to males. As cutaneous collagenous vasculopathy can be clinically indistinguishable from generalized essential telangiectasia, and histopathologic studies are rarely performed for this condition, it is likely that cutaneous collagenous vasculopathy frequently passes unrecognized, but it may be more common than previously thought.

Background In frontal fibrosing alopecia (FFA), scalp alopecia dominates the clinical picture. However, eyebrow loss and hair loss in other body sites may also occur; this has been documented clinically, but rarely histopathologically. We describe the clinicopathological findings of 13 cases of FFA, with histopathologic data from the scalp, eyebrow, and body hair. Methods Thirteen patients with a diagnosis of FFA, seen between 2006 and 2008, were included. Scalp biopsies were performed in all patients for histology and direct immunofluorescence (DIF). Biopsy specimens for histology were taken from the eyebrow in 6 patients and from the upper limb in 5 patients. Results All 13 patients were female, 11 of whom were postmenopausal. The median age at onset of alopecia was 57 years. Clinical examination revealed a band of frontal hairline recession in all patients. Eyebrow loss was present clinically in all patients, with loss of body hair in 10 of 13. Histopathologic examination of the scalp, eyebrow, and upper limb skin biopsy specimens showed similar features, including a marked reduction in the number of hair follicles and a perifollicular lymphoid cell infiltrate with perifollicular fibrosis. Direct immunofluorescence was negative in all cases. Limitations Not all patients consented to biopsies of the eyebrows or upper limbs. Conclusion Eyebrow and peripheral body hair loss is not uncommon in FFA—a finding that is likely underreported. We have demonstrated that alopecia of the upper limbs in FFA is indeed common and, histopathologically, shows features of lichen planopilaris and scarring, similar to findings in the scalp and eyebrows. Consequently, the process of lichen planopilaris with scarring alopecia is generalized rather than localized only to the frontal scalp and eyebrows.

A 56-year-old man with lifelong trauma-induced blisters, nail dystrophy and dental enamel hypoplasia presented with a new spontaneous blistering eruption. Clinicopathologically, he had evidence of both an inherited and an acquired blistering disorder: non-Herlitz junctional epidermolysis bullosa (nHJEB) and bullous pemphigoid (BP). HIstological examination of a skin biopsy found reduced (but not absent) collagen XVII in nonlesional skin, in vivo bound anticollagen XVII antibodies in perilesional skin, and prominent eosinophils in perilesional and lesional skin, with subepidermal blistering. Circulating anticollagen XVII antibodies were also present. Treatment with oral corticosteroids and mycophenolate mofetil led to clinical control of the BP but had no effect on the mechanobullous blistering. Our patient is unusual in that his skin retains some labelling for collagen XVII rather than having the complete absence of immunoreactivity expected in patients with generalized nHJEB. Moreover, we were unable to identify any pathogenic mutations in the COL17A1 gene encoding collagen XVII (or in other EB-associated basement membrane genes). It is plausible that the long-term consequences of basement membrane disruption in our patient, perhaps associated with atypical inherited COL17A1 pathology, might result in a conformationally altered and more immunogenic protein with the subsequent development of anticollagen XVII antibodies and BP as a secondary pathology.

Early lesions of lichen sclerosus et atrophicus (LSA) may present as a mild lichenoid tissue reaction, occasionally together with basilar epidermotropism, mimicking early cutaneous T-cell lymphoma, mycosis fungoides (MF) variant. We report a case of extragenital LSA in which both histological patterns were present in the same clinically homogenous and stable lesion. A 27-year-old man presented with a history of white atrophic plaques on the trunk. A biopsy of an abdominal lesion revealed epidermal thinning, a superficial perivascular lymphoid cell infiltrate with focal epidermotropism, mild nuclear atypia and perinuclear halos. Immunophenotyping showed decreased CD5 and CD7, with a slight predominance of CD8-positive T-lymphocytes. All these changes were suggestive of MF. However, a repeat biopsy 3 months later from the same stable plaque revealed features diagnostic of LSA. LSA mimicking early MF histologically has been reported in genital skin. Conversely, MF may clinically and histopathologically resemble LSA. With gene rearrangement studies, clonal proliferation may not be detected in early MF but has been reported to occur in LSA. Awareness of the histopathologic spectrum of LSA within a stable plaque is important to avoid a potential diagnostic pitfall, and should prompt a repeat biopsy.

Nondermatophytic toenail infection with Scopulariopsis brevicaulis is rare, but may occur often in association with dermatophytes. We report a case of an 84-year-old man who presented with onychomycosis of the big toenail. Histopathologic examination of the avulsed nail showed evidence of S. brevicaulis coinfection with a dermatophyte, despite negative mycology results for the latter. Our case underscores the importance of histopathologic examination of nail specimens as an additional invaluable tool in the diagnosis of onychomycosis, as it may unmask false-negative mycology findings.

Background Scleromyxedema is associated with a monoclonal gammopathy and other comorbidities. Its prognostic and therapeutic features are poorly documented because most reports deal with single cases or small series. Objective We sought to describe the characteristics of patients with scleromyxedema regarding demographics, clinical characteristics, comorbidities, therapeutic interventions, and course. Methods We conducted a retrospective and prospective multicenter study. Results We identified 30 patients with scleromyxedema (17 men and 13 women). The mean age at diagnosis was 59 years. The mean delay between disease onset and diagnosis was 9 months. Monoclonal gammopathy was detected in 27 patients. Extracutaneous manifestations were present in 19 patients including neurologic (30%), rheumatologic (23.3%), and cardiac (20%) manifestations. Two patients developed hematologic malignancies. The most common therapies included oral steroids and intravenous immunoglobulins. Although corticosteroids were ineffective, intravenous immunoglobulins (alone or in combination with other drugs) induced complete remission in 4 and partial remission in 9 patients with a mean treatment duration of 2 years. In all, 21 patients were followed up for a mean period of 33.5 months, at which time 16 patients were alive, 12 with and 4 without skin disease. Five patients died: 2 with dermatoneuro syndrome and 1 each with myeloid leukemia, Hodgkin lymphoma, and myocardial insufficiency. Limitations This is mainly a retrospective study. Conclusions Our study confirms that scleromyxedema is a chronic and unpredictable disease with severe systemic manifestations leading to a guarded prognosis. There is no specific definitive treatment. Our data support the contention that intravenous immunoglobulin is a relatively effective and safe treatment. The response is not permanent and maintenance infusions are required.

High-pressure paint guns deliver paint at approximately 3000 pounds per square inch. At this pressure, paint will penetrate the skin and spread quickly through fascial planes and tendon sheaths. The present case is that of a lesion from the finger of a 35-year-old white male in whom a history was initially unavailable. Histologic examination revealed diffuse fibrohistiocytic proliferation and giant cells, with numerous darkly pigmented, uniformly small-sized particles throughout the lesion. The initial impression was that of a giant cell tumor of tendon sheath. However, the pigment particles were negative for Perls stain, and polariscopic examination revealed clear refractile fragments. These findings raised the possibility that the lesion was the result of a traumatic event. On further inquiry, it was revealed that the patient had sustained a high-pressure paint-gun injury 1 year earlier. The simulation, histopathologically, of a giant cell tumor of tendon sheath by a high-pressure paint-gun injury has not, to our knowledge, been reported previously, nor has the histologic finding of small, uniformly sized pigment particles and polarizable refractile fragments in this particular type of injury.

Frontal fibrosing alopecia (FFA) is a scarring alopecia, now an accepted subset variant of lichen planopilaris (LPP). Its occurrence in males is rare, with only nine cases reported to date. We describe a case of FFA in a male in association with lupus erythematosus. Multiple biopsies from the scalp, eyebrow and arm showed features consistent with LPP, in keeping with the clinical presentation of FFA. Direct immunofluorescence studies showed a positive lupus band test. Further serological investigation confirmed the presence of antinuclear, anticardiolipin and lupus anticoagulant antibodies. Whilst the findings of lupus erythematosus may be coincidental or a forme fruste of the disease occurring in association with FFA, it is feasible that lupus and LPP may occur as an overlap syndrome. This case underscores the importance of multiple biopsies and the role of direct immunofluorescence in disclosing more than one pathology in the follow-up of patients with scarring alopecia.

Background: The clinical presentation of tinea is usually, but not always, characteristic. The purpose of this study was to determine whether the routine use of the periodic acid-Schiff (PAS) stain in inflammatory skin disorders is requisite for identifying clinically undiagnosed tinea cases and to ascertain whether there are histopathologic clues that suggest the diagnosis of a dermatophyte infection. Methods: Hematoxylin and eosin (H&E)-stained slides from 60 PAS-positive tinea cases were examined histologically by two observers. One observer, aware of the diagnosis of tinea, searched for hyphal elements and also recorded in detail epidermal, dermal, and follicular changes. The second observer, not aware of the diagnosis beforehand, reviewed the same slides, together with randomly mixed slides from 21 non-tinea cases, recording the same parameters as the first reviewer. Results: Of the 60 cases of tinea, only 45% were diagnosed clinically. Histologic examination of H&E sections by the two observers disclosed the presence of hyphal elements in 68 and 45%, respectively. No significant histologic differences, except for the presence of hyphae, were observed between tinea and non-tinea cases. Conclusions: The finding that only 57% of PAS-positive cases of tinea showed hyphal elements on H&E examination alone, together with no other differentiable histologic characteristics, lends strong support for the routine use of PAS-staining for inflammatory skin disorders.

A recent paper by Torres‐Cabala et al.1 published in the JCP reports that about 10% (13/136) of small (3 mm or less in size) dysplastic melanocytic nevi show severe architectural disorder, which, however, is almost never coupled with severe cytologic atypia. It is therefore suggested that, in order to avoid overdiagnosis of melanoma, the significance of architectural changes of small melanocytic lesions must be interpreted with caution; the small size of the lesion hampers the evaluation of some of these criteria (symmetry, confluence of junctional nests and degree of single cell proliferation).

Background: The histopathologic findings of localized reactions to tick bites may present as diagnostic dilemmas, especially if there is no history of a tick bite, or if the tick's mouthparts are not present in the biopsied skin. Objective: Skin biopsies of patients with a clinical history of a tick bite were selected and reviewed with the aim of detecting a common histopathologic denominator which could serve as a useful clue to the diagnosis, especially when the tick's mouthparts are absent. Methods: Hematoxylin and eosin-stained slides of 15 skin biopsies of tick bites were retrieved from three dermatopathology and pathology laboratories. Where additional paraffin-embedded tissue was available, additional sections were also stained with periodic acid-Schiff (PAS) and phosphotungstic acid-hematoxylin (PTAH). Results: In every case in which adequate tissue was available (13/15 biopsies), the capillaries and postcapillary venules of the superficial and deep vascular plexi adjacent to the attachment's site were filled with thrombi. Fibrin thrombi were seen in association with other more numerous thrombi characterized by homogeneous eosinophilic hyaline material similar to the cryoprecipitate present in type I (monoclonal) cryoglobulinemia. All thrombi were positive for PAS and PTAH; however, the latter staining was minimally present in the hyaline thrombi. In most cases, the site of the tick bite showed ulceration, with an underlying wedge-shaped superficial and deep perivascular and occasionally interstitial mixed lymphohistiocytic infiltrate. In addition, there were eosinophils, numerous neutrophils and extravasated erythrocytes. Other findings included suppurative necrosis (7/15) cases, giant-cell reaction (one case), fat necrosis (one case) and eccrine gland necrosis (one case). Conclusions: Vascular eosinophilic hyaline thrombi were found to be a frequent histologic manifestation of a tick bite. This finding may be related to the secretory products of the tick's saliva during inoculation. We believe that a tick bite should be suspected when focal intravascular hyaline occlusion is observed, and that it should be included in the differential diagnosis of type I (monoclonal) cryoglobulinemia, even if there is no history of a tick bite or if tick parts are not present in the skin biopsy specimen.

Background: Tumor of the follicular infundibulum (TFI) is a relatively rare tumor which clinically presents as a solitary keratotic papule usually on the head and neck which on microscopic examination typically reveals a plate-like fenestrated epithelial tumor composed of pale staining cells. Methods: We describe a new variant of TFI. An 80-year-old male with a history of multiple basal cell carcinomas and a squamous cell carcinoma presented with a 2-year history of a red, scaly, slightly elevated plaque on the lateral aspect of his right buttock. Results: Histopathological examination revealed plate-like reticulate epithelial outgrowths of large and pale cells with foci of sebaceous differentiation and numerous colloid bodies. Differential diagnosis included superficial basal cell carcinoma with sebaceous and ductal differentiation, tumor of the follicular infundibulum, an unusual fibroepithelioma of Pinkus or an eccrine fibroadenoma with sebaceous differentiation. Conclusion: This case illustrates a hybrid adnexal tumor with histologic features common to both tumor of the follicular infundibulum and superficial epithelioma with sebaceous differentiation.

Atypical moles (dysplastic nevi) are important markers for persons at increased risk for developing melanoma 1, 12 and are potential precursors to melanoma. 9 The clinical characteristics that distinguish an atypical mole are those normally attributed to melanoma, the ABCD s of dermatology: (A) asymmetrical shape or contour, (B) border irregularity, (C) color variegation, and (D) diameter greater than 6 mm. 8, 32 These criteria help differentiate atypical moles from common nevi clinically; however, because the criteria for melanoma are similar to those for atypical moles, a tendency to overdiagnose melanoma results. The difference between an atypical mole and melanoma is primarily dependent on the extent of these features; that is, the more dysmorphic the lesion, the more likely is a diagnosis of melanoma. Reliably differentiating atypical moles from early melanomas poses a considerable challenge to the clinician. Dermatologists correctly diagnosis melanoma about 65% of the time. 10, 15, 18, 24 In an attempt to improve on this rate, various noninvasive methods have been investigated as possible aids for the early diagnosis of melanoma, the most promising being dermoscopy (epiluminescence microscopy [ELM]). 28, 29, 33, 37 Dermoscopy increases the diagnostic accuracy for melanoma, particularly when the clinician is experienced with its use. 4, 5, 16, 25, 26, 28, 37 Despite the improvement in diagnostic accuracy with dermoscopy, a significant number of melanomas are missed by this technique. The reported sensitivity of dermoscopy for melanoma ranges from 62% to 94%. 5, 6, 16, 25, 26, 28, 34, 37 Although pathognomonic dermoscopic findings for melanoma have not been identified, 36 several are highly suggestive. These findings include an irregular pigment network with abrupt margins, radial streaming, pseudopods, depigmented areas, a whitish veil, brown globules and black dots of variable size and irregular distribution, and homogeneous areas. 14, 23, 28, 29, 34, 36 In general, a combination of features must be present to conclude with any certainty that a given lesion is benign or malignant. 17, 28, 36 Up to 10% of melanomas may be featureless, 22 probably accounting for the high rate of false-negative results reported by some investigators. 5, 26 In our study discussed herein, the usefulness of the aforementioned dermoscopic features is reexamined in differentiating early melanomas from atypical moles. Attempts also are made to identify potential new criteria for early melanoma detection by subjectively quantifying or characterizing dermoscopic structures.

A 26-year-old Libyan woman presented with asymptomatic nodulo-ulcerative skin lesions present for 1 year. Three years prior to presentation, she had experienced a nasal discharge followed by the development of a nodule in the nasal cavity and a plaque on the hard palate. These lesions had gradually increased in size and ulcerated, resulting in perforation of the nasal septum and palate. Two years later, the patient noticed the appearance of skin lesions: a nodule on the right thumb and numerous nodulo-ulcerative lesions on the extremities. General physical examination was normal with no significant lymphadenopathy. Examination of the oral cavity revealed perforation of the distal nasal septum, with a perforated nodular plaque involving the entire palate, associated with subluxation of the upper incisors (Fig. 1a). On skin examination, multiple firm nodules and nodulo-ulcerative lesions with a central eschar and raised margins were observed. The lesions ranged in size from 0.5 to 5 cm and were distributed on the right hand and fingers, left upper arm (Fig. 1b), left calf, and right thigh. Routine laboratory investigations (liver function tests, serum calcium, electrolytes, lipid profile, urine and stool culture studies) were normal. Immunoelectrophoresis disclosed normal levels of immunoglobulins IgG, IgA, and IgM. Serologic studies for human immunodeficiency virus (HIV) and syphilis, and a tuberculin test, were all negative. A Giemsa-stained tissue smear was negative for Leishmania tropica organisms. Radiological studies disclosed a slight haziness of the maxillary sinuses with perforation of the nasal septum. A chest X-ray was normal. Histopathologic examination of biopsies taken from both the palate and from ulcerated and nonulcerated skin lesions was performed, and all showed similar findings. The biopsy of a nonulcerated skin lesion showed pseudoepitheliomatous epidermal hyperplasia with neutrophilic microabscesses (Fig. 2a). A dermal diffuse and nodular granulomatous mixed infiltrate of lymphocytes, histiocytes, giant cells, numerous eosinophils, and neutrophilic microabscesses was seen in all tissues examined. Septate hyphae were present both within giant cells and free in the dermis (Fig. 2b). The hyphae were branching at a 45 degrees angle and were positive on periodic acid-Schiff and Grocott methenamine silver stains (Fig. 2c). Fungal culture studies of material taken from an ulcerated skin lesion grew Aspergillus flavus. Blood cultures were negative for Aspergillus sp. or other microorganisms. The patient was treated with intravenous amphotericin B, but the medication was discontinued due to her intolerance to the drug. She was subsequently lost to follow-up.

Extramammary Paget disease (EMPD) is a heterogenous entity representing either an intraepidermal adenocarcinoma in situ with apocrine differentiation or an expression of underlying malignancy of the skin or of the intestinal or genitourinary tract. The coexistence of EMPD with a benign underlying hidradenoma papilliferumn (HP) is, however, exceptional. We present the case of a 79-year-old woman with diffuse and patchy gray-white lesions involving her left vulva as well as an underlying 0.7-cm asymptomatic firm nodule. Histologically, the epidermis and dermis showed features characteristic of EMPD and HP, respectively. Malignant transformation in HP giving rise to EMPD in the overlying epithelium has been reported. In our case, however, failure to demonstrate continuity between the two lesions together with the lack of cytologic atypia, mitoses, and necrosis in the HP lends additional support to the possibility that the HP is "innocent" and that its association with EMPD is thus coincidental. A common histogenetic derivation of these two lesions from the mammary-like glands or from related germinative cells in the epidermis is suggested to explain this rare presentation.

We report a case of localized bullous pemphigoid (BP) in a woman patient with primary lymphoedema tarda. There is only one previous case reported of localized pemphigoid in an area of lymphoedema, this being of the cicatricial variant. Slow circulation in the lymphatic vessels, increased capillary permeability with preferential localization of antibodies in the area, and potential cleavage of the epidermal junction due to increased hydrostatic pressure leading to autoimmunity, have all been advocated as possible pathogenic mechanisms. Nevertheless, we consider that the mechanism by which localized pemphigoid arises on lymphoedema remains elusive, based on a previous case of generalized BP sparing an area of postsurgical lymphoedema.

We report a unique case of a congenital keratinocytic naevus associated with severe alopecia, onychodysplasia and palmoplantar involvement in a 13-year-old girl. The lesions, consisting of scaly, spinous and verrucous papules and plaques, mainly followed Blaschko's lines and have remained unchanged since birth. The predominant histopathological picture was that of a column of parakeratosis overlying the eccrine ostia and hair follicles. This is the first case of a systematized keratinocytic naevus characterized by histopathology of eccrine and hair follicle porokeratosis and a widespread bilateral involvement. This may be a distinct entity to be included in the differential diagnosis of linear, hyperkeratotic dermatoses. We suggest its classification as systematized porokeratotic eccrine and hair follicle naevus.