Cutaneous perineural inflammation: a review

Basal Cell Carcinoma Perineural Invasion and Suggestive Signs of Perineural Invasion-Findings and Perspectives

Basal cell carcinoma (BCC) is a malignant tumor with a rising incidence and is the beneficiary of several innovative evaluation techniques. Histopathology remains the gold standard for assessment, having the possibility of addressing multiple high-risk factors such as perineural invasion (PNI). The current study included a number of 244 BCC patients and targeted the identification of positive PNI and its suggestive signs, and whether they correlated or not with other high-risk tumor signs. PNI was found in 20.1% of patients, with 30.7% of patients having perineural chronic inflammation (PCI), which is a suggestive sign of PNI. PNI was also found in larger tumors, with deeper Clark levels, in high-risk BCCs and high-grade tumors. PNI and PCI are both important for pathology reporting, aiding in treatment choice and further patient management, with possibly positive outcomes concerning morbidity and mortality.

Review of Perineural Invasion in Keratinocyte Carcinomas

Perineural invasion is an infiltrative process of peripheral nerves by the primary neoplasm within the immediate vicinity. Aggressive forms of keratinocyte carcinomas, such as basal cell and squamous cell carcinomas, may feature perineural invasion, which is often associated with tumor recurrence and poorer prognosis. Diagnosis requires a high clinical suspicion. Imaging and histopathology are used to assess for extent of disease while surgical excision with complete circumferential peripheral and margin assessment is the treatment goal. However, there is still significant uncertainty about adjuvant chemotherapy and definitive management guidelines. Here, we summarize the current understanding of this complex pathogenic process, the clinical presentation, and the significance of perineural inflammation. We also discuss the recommendations about staging, prognosis, adjuvant radiotherapy, and general guidelines for managing keratinocyte carcinomas with perineural invasion. A better understanding of perineural invasion is essential to improve diagnosis, tailor interventions, and mitigate patient morbidity and mortality.

Effects of Human Interleukin-10 on Ventilator-Associated Lung Injury in Rats

Ventilator-induced lung injury (VILI) is one of the most serious complications of mechanical ventilation (MV) and can increase the mortality of patients with acute respiratory distress syndrome (ARDS). This work aimed to test the hypothesis that the anti-inflammatory properties of human interleukin-10 (hIL-10) can reduce VILI. Thirty-six healthy male Sprague-Dawley rats were randomly assigned into three groups (n = 12) as follows: a control group, a VILI group, and a hIL-10 group. Lung function was evaluated by oxygenation index and pulmonary edema, and morphological changes associated with lung injury were assessed by HE staining and quantitative histological lung injury score. Malondialdehyde (MDA) and Superoxide dismutase (SOD) were measured, and the levels of various inflammatory cytokines were assessed in BALF and plasma. The oxygenation index in the VILI group decreased significantly relative to the control group and improved substantially in the hIL-10 group (P < 0.01). Compared to the control group, MDA production was stimulated (P < 0.01), and SOD activity rapidly declined (P < 0.01) in the VILI group. After hIL-10, MDA content was lower than that seen in the VILI group (P < 0.01), and SOD activity was enhanced (P < 0.01). The VILI group had the highest cytokine levels, compared to either the hIL-10 group or the control group (P < 0.05). High tidal volume MV can induce VILI. hIL-10 may regulate the inflammatory response in the lung tissue, improve lung tissue oxygenation, and inhibit oxidative stress, therefore reducing VILI in rats. These experiments reveal a potential new treatment option for VILI.

A Case of Circumscribed Scalp Morphea with Perineural Lymphocytes on Pathology

Scalp morphea presents as a scarring alopecia in en coup du sabre pattern. We report an unusual presentation of a round hairless patch of morphea on the occipital scalp present for 15 years. The scalp lesion aligned with 2 other hyperpigmented lesions of biopsy-proven morphea in the lower back. Pathology of horizontal sections from the scalp lesion showed follicular dropout, thickening of the collagen bundles, and preserved eccrine and follicular structures. Marked lymphocytic perineural infiltrate, a reported clue to the diagnosis of scalp morphea, contributed to the diagnosis. This case is unusual due to its rare clinical presentation. It also highlights the importance of recognizing histopathological clues for the diagnosis of uncommon scalp disorders.

Borderline Tuberculoid Leprosy Masquerading as Granuloma Annulare: A Clinical and Histological Pitfall

INTRODUCTION

Leprosy is a chronic granulomatous disease caused by Mycobacterium leprae, an intracellular acid-fast bacillus that tends to infect the skin and peripheral nerves. Because of the wide array of cutaneous manifestation, diagnosis is not always straightforward, especially in nonendemic regions of the world such as the United States.

CASE REPORT

The authors report an unusual case of borderline tuberculoid leprosy in an 80-year-old white woman from California. Clinical examination revealed multiple nonscaly annular plaques, with central clearing and absence of lesional anesthesia, distributed over the trunk and extremities initially clinically diagnosed as granuloma annulare (GA). After 2 years of unsuccessful treatment with topical corticosteroid, biopsy revealed a palisaded and interstitial granulomatous infiltrate with necrobiosis, without discrete granulomas, compatible with GA. However, the presence of perineural lymphocytes in the reticular dermis prompted a Fite stain, which revealed acid-fast bacilli within the Schwann cells of a small peripheral nerve, pathognomonic for leprosy.

CONCLUSION

This is the first reported case of leprosy masquerading both clinically and histologically as GA. Dermatopathologists should be aware of the possibility of leprosy given the presence of perineural lymphocytes amidst any pattern of granulomatous infiltrate and obtain a Fite stain.

Histopathologic pitfalls of Mohs micrographic surgery and a review of tumor histology

Mohs micrographic surgery is a specialized subset of staged surgical excisions with each subsequent stage being driven largely by the histologic findings of the previous stage. Therefore, it is imperative that histologic analysis is performed in an accurate manner. Frozen section and tissue flattening is a crucial step in Mohs surgery. Frozen sections introduce certain artifacts and these artifacts must be interpreted in the correct context. Basal and squamous cell carcinomas are the most common tumors encountered in Mohs micrographic surgery, and their histopathology is also associated with certain "pitfalls". Basal cell carcinoma should be distinguished from hair follicles, folliculocentric basaloid proliferations, poromas, nevus sebaceous, desmoplastic trichoepitheliomas, and spiradenomas, to name but a few histologic entities. Similarly, squamous cell carcinoma should be distinguished from hypertrophic actinic keratoses, pseudoepitheliomatous hyperplasia, sebaceous carcinoma, and microcystic adnexal carcinoma. In addition, there are numerous subtypes of basal cell and squamous carcinomas that the Mohs surgeon should be aware of due to differences in the biologic behavior of these tumors. This review presents a number of the common histologic pitfalls of Mohs micrographic surgery and a review of tumor histology.

Perineural and intraneural cutaneous granulomas in granulomatous mycosis fungoides mimicking tuberculoid leprosy

BACKGROUND

Histological similarities between granulomas and granulomatous mycosis fungoides (GMF) may lead to misdiagnoses of sarcoidosis or leprosy.

METHODS

This report presents four patients with GMF in whom skin biopsies showed perineural and intraneural granulomas that were confused with tuberculoid leprosy granulomas.

RESULTS

Patient 1 presented with erythematous plaques and bulky nodules. Biopsy findings suggested cutaneous sarcoidosis. Tumor resection showed granulomatous infiltrate extending to the fascia and skeletal muscle. Clinicopathological correlations permitted a diagnosis of GMF. Patient 2 presented with erythematous plaques. Skin biopsies had indicated sarcoidosis. Resection of a thigh nodule excluded leprosy, and GMF was diagnosed. Patient 3 presented with scaly, hyperpigmented plaques. Biopsy showed diffuse granulomatous inflammation with epithelioid and giant cells, abundant lymphocytes, and some eosinophils, and indicated GMF. Patient 4 presented with pruritic, erythematous plaques. Biopsy of an indurated mammary plaque initially indicated sarcoid granulomatous inflammation. Biopsy review suggested GMF.

CONCLUSIONS

This study highlights both the diagnosis of GMF, and granulomatous cutaneous nerve injury in GMF and its possible confusion with leprosy granulomas. The histological diagnosis of GMF includes: (i) a granulomatous infiltrate rich in giant cells, emperipolesis, histiocytic cells, and scattered eosinophils, which may reach the fascia and muscle; (ii) the absence of elastic fibers or their phagocytosis by giant cells; and (iii) lymphocytes that may show atypia and epidermotropism. Deep biopsies reveal GMF diagnostic changes and, in conjunction with clinicopathological correlations, exclude a diagnosis of leprosy and support one of GMF, thus facilitating its appropriate management.

Sarcoid-like paracoccidioidomycosis presenting with perineural granuloma

Paracoccidioidomycosis presenting as a sarcoid-like plaque may be misdiagnosed as leprosy, especially when shared endemic areas are concerned. We report the case of a Brazilian male patient presenting with an ulcerated plaque on his left ear and neighboring areas. The plaque simulated tuberculoid leprosy type 1 reaction, both clinically and histopathologically. A perineural granuloma with no organisms detected by routine and Fite-Faraco staining reinforced that diagnosis. Paracoccidioidomycosis was confirmed only after a second biopsy, taken from the ulcerated area.

Neurotropic T-cell lymphocytosis: a cutaneous expression of CLIPPERS

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an inflammatory disease of the central nervous system that predominantly involves the pons and cerebellum and that improves with immunosuppressive treatment. Only recently described, the etiology is unknown, diagnosis is difficult and long-term neurological sequelae may occur without aggressive treatment. Herein, we describe a 59-year-old woman who presented with subcutaneous nodules affecting her face, trunk, limbs and an indurated annular erythematous lesion on her forearm. This was associated with marked dysesthesia of her skin, refractory to treatment. There was a 4-year history of dysequilibrium, vertigo, truncal and gait ataxia with progressive neurological symptoms. Skin biopsy of the annular nodular lesion showed a lymphohistiocytic infiltrate in dermis and subcutis with a striking lymphocyte-dominant infiltrate that was perineural and formed a nodular collection extending along a prominent subcutaneous nerve. Immunophenotyping indicated a marked predominance of T cells that were CD3 positive with a 2 : 1 CD4 : CD8 ratio. Scattered histiocytes were present but no well-formed granulomas or vasculitis. Magnetic resonance imaging studies showed changes in the pontine, brain stem and cerebellar region, which subsequently were defined as characteristic for CLIPPERS, but no brain biopsy was pursued. The marked neural skin symptoms and the cutaneous histopathological findings indicate that the skin may be an additional target organ in CLIPPERS, and the immune response may be directed against a common neural antigen. In radiologically typical CLIPPERS, identification of clinical skin lesions particularly subcutaneous nodules and biopsy may potentially form a basis for tissue diagnosis in this syndrome.

Current knowledge in inflammatory dermatopathology

The complex and fascinating spectrum of inflammatory skin disease, and the comprehension of it, is ever expanding and evolving. During the first decade of the 21st century, numerous advances in the understanding of inflammatory disease mechanisms have occurred, particularly in psoriasis and atopic dermatitis. Continuation of this trend will assure a future in which molecular tests for biomarkers of immediate clinical relevance are used in routine patient care, not only for diagnosis but also for prognosis and management. This article focuses on selected recent or noteworthy developments that are clinically relevant for the histologic diagnosis of inflammatory skin diseases.

Alopecia with perineural lymphocytes: a clue to linear scleroderma en coup de sabre

Linear scleroderma en coup de sabre ('the stroke of the sword') is an uncommon form of morphea with onset typically in childhood or adolescence. Involvement is usually located on the paramedian forehead and is associated with alopecia. It is microscopically indistinguishable from other forms of scleroderma. We present a 51-year-old woman who presented with alopecia and subsequently developed linear scleroderma en coup de sabre on her adjacent forehead. Histopathology revealed a strikingly perineural lymphocytic and plasmacytic infiltrate, extending deeply into the subcutis and fascia. To our knowledge, this is the first report of alopecia with perineural lymphocytic inflammation as a presenting sign of linear scleroderma en coup de sabre.