Elena Castelli

Local reactions to tick bites.

A retrospective histological and immunohistochemical study has been carried out in 25 cases of tick bites recorded in our Departments. The samples that included an attached tick showed a cement cone anchoring the mouthparts to the skin and a blood-soaked, spongiform appearance of the superficial dermis, with a mild neutrophilic and eosinophilic infiltration. The vessels displayed a loose multilayered endothelial proliferation, with plump endothelia, permeated with erythrocytes. A few of them were severed, allowing copious blood extravasation. The established lesions included the following: erythema chronicum migrans-like cases, foreign body granulomas-sometimes containing remnants of the mouthparts-cutaneous lymphoid hyperplasia, either of the T-cell or the B-cell type, and tick-bite alopecia. In both the T-cell and B-cell pseudolymphomas, several vessels showed concentric endothelial and perithelial proliferation similar to that seen in the acute lesions. In the tick-bite alopecia, a lymphocytic infiltrate attacked the permanent portion of the hair follicles, whose reaction was a noticeable hyperplasia of the fibrous sheaths, although only a minority of the hairs was destroyed. The observed alterations are specific in the acute lesions and in the alopecia, where they directly arise as a result of the interactions between the hosts tissues and the antihemostatic, anti-inflammatory, and immunomodulatory chemicals contained in the tick saliva. In the other lesions, the changes seem less characteristic, although the fragments of mouthparts and the special vascular changes provide a clue to their etiology.

Extramammary Paget Disease of the Axilla Associated With Comedo-like Apocrine Carcinoma In Situ.

Extramammary Paget disease of the axilla with underlying apocrine carcinoma has been reported only in six cases until now. This report deals with a seventh case characterized by the unique finding of comedo-like features evocative of large cell ductal breast carcinoma within an otherwise typical in situ apocrine carcinoma. This is characterized by spiral-shaped foci of epithelial proliferation with decapitation secretion and central masses of necrotic debris. A possible connection between the solid neoplasm and the overlying Paget disease is illustrated by a few apocrine-follicular units colonized by both the Paget cells and the structured adenocarcinoma. Here, although they display the same immunohistologic pattern of glandular differentiation, the two populations seem to be cytologically different and do not show signs of gradual transition to one another. Thus, they give the impression of parallel but distinct processes, which is consistent with the hypothesis of proliferative induction of a preexisting intraepidermal scattered population from the underlying adnexal carcinoma. The observed resemblance between apocrine carcinoma and comedo carcinoma of the breast, with its ontogenetic and phylogenetic implications, links not only the two neoplasms and the corresponding glands of origin but also mammary and extramammary Paget disease. This reinforces the unifying conception of Paget disease.

Avian mite dermatitis: an Italian case indicating the establishment and spread of Ornithonyssus bursa (Acari: Gamasida: Macronyssidae) (Berlese, 1888) in Europe.

Avian mite dermatitis is a skin disease caused in mammals by the incidental bites of blood‐sucking mites which customarily parasitize wild and domestic birds. It manifests in the form of pruritic, erythematous, or urticarial papules, with a central sting mark, in skin regions normally covered by clothing. The species mainly implicated in human bite cases are Dermanyssus gallinae, Ornithonyssus sylviarum and, less frequently, Ornithonyssus bursa. The latter is mainly a tropical and subtropical mite and its – presumably transitory – presence has been recorded only once in Europe, in migratory birds.

Perineural Pattern of Aggregation of Cellular Blue Nevus : Probable Histoarchitectural Reminiscence of Histogenesis

A striking feature of cellular blue nevus consists in the presence, in its histologic picture, of numerous hypertrophic nerves and nerve-like figures, positive for histochemical and immunohistochemical methods for nerve fibers and myelin sheaths. These findings, first described in Massons original article and repeatedly highlighted in the past for their possible histogenetic significance, are currently considered as merely coincidental. However, the thin conventional histologic sections, catching only short tracts of the nerves, preclude a correct observation of their route and do not allow us to verify if there is an architectural relationship between them and the nevus as a whole. With this aim, we observed a few specimens of cellular blue nevus on digitally overlapped images of contiguous 25-μm-thick sections, processed with Winkelmanns technique of silver impregnation for nerve fibers, which supplied an overall, 3-dimensional view of the lesions and the nerves running through them. In these images, the lobular form of the nevus could be seen gathering around a branching hypertrophic nerve, whose stem stretched vertically from the depth to the most superficial tract of the lesion. The nevus cell aggregates invested the stem and the limbs individually, and these followed the curvilinear contour of the nevus lobules. Our images represent evidence of a preferential perineural aggregation of cellular blue nevus, at least in its lobular form. This indicates that the numerous nerves and the neuroid figures, observed in detail-but within a limited perspective- in the conventional sections, are not merely coincidental and they could indeed be a sign of neural differentiation and/or a clue to the possible neural origin of the nevus.

Dermatitis due to Mesostigmatic mites (Dermanyssus gallinae, Ornithonyssus [O.] bacoti, O. bursa, O. sylviarum) in residential settings

Since early recorded history, people who live in urban areas have shared their environment with pets and synanthropic animals, mainly birds and rodents. These animals harbor zoonotic parasites, including mites of the suborder Mesostigmata [ 1 ] . Among them, the avian mites Dermanyssus (D.) gallinae , Ornithonyssus (O.) sylviarum, O. bursa and the tropical rat-mite, O. bacoti are the most dermatologically relevant species. They are non-burrowing, bloodsucking ectoparasites of similar shape and size (about 1 mm in length) [ 1 ] . With the exception of O. sylviarum, which usually lives permanently on its host, they are temporary and nocturnal visitors of their victims, hiding in daytime in their close proximity. The resting/breeding sites of birds/ rodents, mainly pigeons and feral rats/mice and occasionally pets, act as mite reservoirs [ 2, 3 ] ; in the absence of their natural host, hungry mites may migrate into nearby human buildings and bite their inhabitants. Patients develop itching urticarial papules, often bearing a red punctiform mark, on covered and/or exposed body areas. These lesions are usually unrecognized unless there is a high degree of clinical suspicion. From 2001 to September 2017, we used transmission light microscopy and/or scanning electron microscopy to analyze the arthropods supposedly related to 26 urban outbreaks of pruritic dermatitis, with a total of 66 subjects (60 adults and 6 children) living and/or working in southern peninsular and insular Italian regions (Campania, Molise, Basilicata, Apulia and Sicily). The dermatitis had started in spring/summer and lasted from a week to nine months. In eleven cases, it remained undiagnosed for more than four weeks and underwent several relapses after systemic and local treatment with antihistamines and corticosteroids. The patients presented with eruptions of urticarial papules, most of which had a central red puncture mark, readily detectable with a magnifi cation lens (Figures 1, 2 ). The clinical picture was highly suggestive of mite bite dermatitis and the parasites were searched for. They were collected from the patients’ bedrooms, workplaces (hospitals, offi ces, animal facilities) and from the patients’ skin. In a few cases, the parasites were delivered to our laboratory by the patients themselves, who had found them crawling on their skin and/or in their bedrooms or workplaces. The parasites were identifi ed as D. gallinae (20/26; peninsular regions), O. bacoti (4/26; Sicily/peninsular regions), O. bursa and O. sylviarum (both 1/26; Sicily) based on morphological key characters [ 1, 4 ] (Figure 3 ). Abandoned bird nests (20/26; pigeon/sparrow/ swallow) close to buildings, pet canaries (1/26) and poultry in backyards (1/26) were the sources of avian mite species; the source of O. bacoti was ascribed to laboratory holdings (1/26) or colonies of wild rats (3/26). Considering the patients’ medical histories, clinical fi ndings and laboratory data, we diagnosed Mesostigmata mite infestation in all cases. Showering and washing clothes, removal of mite sources and

Centrifugal necrotic keratoacanthoma

Centrifugal necrotic keratoacanthoma is a quite rare variant of keratoacanthoma, with a locally aggressive behavior and no tendency to spontaneous involution. We report a typical case of the nasal-orbital region. Based on its clinical, histological and behavioral picture, centrifugal necrotic keratoacanthoma appears as variant of giant keratoacanthoma and can be regarded as an intermediate form in a spectrum where keratoacanthoma and overt squamous cell carcinoma represent the most benign and the most malignant end, respectively, as also highlighted by analogies between the two lesions recently reported in the field of molecular biology.