Locus minoris resistentiae: An old but still valid way of thinking in medicine

Epstein-Barr Virus-Associated Lymphomatoid Papules: A Sign of Immunosuppression Resembling Lymphomatoid Papulosis

ABSTRACT

Epstein-Barr virus (EBV)-positive lymphoproliferative disorders associated with immunodeficiency constitute a spectrum of lymphoid and plasma cell proliferations that vary in cytomorphology, immunophenotype, and clinical behavior. CD30-positive cutaneous lymphocytic infiltrates with EBV expression and lymphomatoid papulosis-like presentations have been rarely reported. This retrospective study assessed the clinical and histopathological characteristics of EBV-positive cases with papulonodular morphologies and CD30 positivity seen by Northwestern Medicine Dermatopathology. Twelve patients (7M:5F, mean age 69 years) were presented with papular cutaneous lesions without antecedent patch/plaque disease. Nine cases were associated with known immunosuppression in the setting of transplant-related therapies (n = 4), hematopoietic malignancy (n = 2), post-transplant hematopoietic malignancy (n = 1), and autoimmune disease treatment (n = 2). Two patients had age-related immunosenescence. Four patients demonstrated EBV viremia; for 2 patients, this finding comprised the first sign of immunosuppression. Workup was negative for systemic lymphoma in all patients. Various treatment strategies were used, including observation (n = 3), discontinuation/reduction of immunosuppression (n = 3), rituximab (n = 4), and steroids (n = 4). At mean 30-month follow-up, 4 patients (33.3%) were alive, 3 with and 1 without disease. Eight patients (67.6%) had died, 3 after lesional resolution and 5 with recurrent disease. Biopsies revealed mixed lymphoid infiltrates composed of atypical CD30-positive T cells (n = 5) or B cells (n = 7) with variable EBV-encoded small RNA expression. These cases suggest clinicopathologic presentations resembling lymphomatoid papulosis with atypical, large CD30-positive, EBV-positive cells could comprise first sign of potentially serious immunodeficiency and should prompt evaluation for EBV viremia. These cases also broaden the current picture of immunodeficiency-associated lymphoproliferative disorders to include lymphomatoid papulosis-like clinical presentations.

Morphological and Physiological Aspects of Mutable Collagenous Tissue at the Autotomy Plane of the Starfish Asterias rubens L. (Echinodermata, Asteroidea): An Echinoderm Paradigm

The mutable collagenous tissue (MCT) of echinoderms has the capacity to undergo changes in its tensile properties within a timescale of seconds under the control of the nervous system. All echinoderm autotomy (defensive self-detachment) mechanisms depend on the extreme destabilisation of mutable collagenous structures at the plane of separation. This review illustrates the role of MCT in autotomy by bringing together previously published and new information on the basal arm autotomy plane of the starfish Asterias rubens L. It focuses on the MCT components of breakage zones in the dorsolateral and ambulacral regions of the body wall, and details data on their structural organisation and physiology. Information is also provided on the extrinsic stomach retractor apparatus whose involvement in autotomy has not been previously recognised. We show that the arm autotomy plane of A. rubens is a tractable model system for addressing outstanding problems in MCT biology. It is amenable to in vitro pharmacological investigations using isolated preparations and provides an opportunity for the application of comparative proteomic analysis and other “-omics” methods which are aimed at the molecular profiling of different mechanical states and characterising effector cell functions.

“Locus minoris resistentiae” and connective tissue weakness in older women: a case report and literature review on pelvic organ prolapse with inguinal bladder hernia

Background

Conditions such as genital prolapse and hernia are known to be related to connective tissue dysfunction. In this report on cases of the rare simultaneous finding of large genital prolapse and post-prolapse repair female inguinal bladder hernia, we aim to contribute to the discussion of a possible clinical definition of connective tissue weakness, for its clinical assessment and preoperative patient counselling.

Case presentation

Three cases of medial third-grade (MIII, Aachen classification) inguinal bladder hernia developing or enlarging after successful stage-IV pelvic organ prolapse (POP) repair at a university pelvic floor centre are presented. All patients were aged ≥ 80 years with long-standing postmenopausal status. One patient was followed for 5 years and two patients were followed for 6 months. In all patients, ultrasound revealed that the hernia sac contained the urinary bladder, which had herniated through the inguinal hernia orifice. A literature search revealed only one case report of direct female inguinal bladder hernia and few investigations of the simultaneous occurrence of POP and hernia in general.

Conclusion

The simultaneous occurrence of inguinal hernia and female POP can lead to bladder herniation following prolapse surgery in the sense of a “locus minoris resistentiae”. Clinical examination for simultaneous signs of connective tissue weakness and counselling prior to pelvic reconstructive surgery could help to increase patients’ compliance with further surgical treatment for hernia.

Locus Minoris Resistentiae: Two Cases of Malignant Metastasis and Review of Literature

Locus minoris resistentiae refers to a region of decreased resistance within the body. This occurs from changes to the microenvironment secondary to previous trauma and results in increased vulnerability. As a result, infection, inflammatory processes, and malignancy may localize to this area. In this article, we describe 2 unique cases of malignancy, primary prostate carcinoma and serous carcinoma of the ovary, both of which disseminated to sites of prior trauma. We review the available literature, discuss proposed pathophysiology, and highlight the need for further investigations along with increased clinician awareness.

Compartment Syndrome Secondary to Group A Streptococcus Infection in the Presence of a Congenital Hemangioma

OBJECTIVES

Nontraumatic compartment syndrome is frequently difficult to diagnose but this is especially troublesome in infants. Pain is the most sensitive sign and is characteristically severe and refractory to routine analgesia. Failure to diagnose and treat can lead to disability, multiorgan failure, and death. Surgical intervention is crucial and includes emergent fasciotomy, debridement, nerve decompression, and later skin grafting. Streptococcal myositis causing compartment syndrome is more likely in the immunocompromised patient.Congenital hemangiomas are rare, benign vascular tumors that present fully grown at birth.

METHODS

Case report and literature review.

RESULTS

This case report details a healthy child, with a resolving congenital hemangioma of the forearm, presenting with toxic shock syndrome and a streptococcal myositis creating a compartment syndrome in the same forearm after an upper respiratory tract infection. The child underwent an emergent fasciotomy and debridement of the arm. Profound systemic effects necessitated transfer to intensive care unit and continuing postoperative mechanical ventilation, inotropic support, intravenous antibiotics, and immunoglobulin administration. Postoperatively, blood cultures and wound biopsies were all positive for Beta Hemolytic Group A Streptococci. Several days later, after a course of antibiotics, the volar forearm was closed with meshed split thickness skin grafts with good graft take. In our patient, we concluded that the hemangioma may have acted as a locus to attract the hematogenous spread of the streptococcal infection from the throat and caused a soft tissue infection that led to massive edema of the limb and consequently to compartment syndrome.

Locus Minoris Resistentiae in Coccidioidomycosis: A Case Series

Locus minoris resistentiae refers to decreased resistance in any internal organ or external body region, leaving it more vulnerable to disease processes than other regions. These changes, either congenital or acquired, alter the defense capacity. The concept of locus minoris resistentiae is widely accepted in the medical field and presents itself across specialties. Antecedent trauma is a known risk factor for hematogenous dissemination of infection; this also applies to coccidioidal species. In this article, we describe 2 patients who suffered from pulmonary coccidioidomycosis with subsequent trauma resulting in osseous dissemination to the site of injury.

Mycobacterium Avium complex vertebral osteomyelitis in the absence of HIV infection: a case report and review

BACKGROUND

Mycobacterium Avium Complex (MAC) is an established microbiologic cause of pulmonary disease, lymphadenitis, and disseminated disease in cases of advanced immune suppression. However, MAC manifesting as vertebral osteomyelitis is less common, and is particularly rare in the absence of Acquired Immunodeficiency Syndrome (AIDS). Prompt diagnosis of MAC vertebral osteomyelitis is challenging, but necessary to prevent serious morbidity or mortality.

CASE PRESENTATION

We report a case of MAC osteomyelitis of the lumbar spine in a 70-year-old woman on extended duration corticosteroid therapy for systemic lupus erythematosus who presented with progressive back pain. Upon presentation, imaging revealed osteomyelitis of the lumbar spine with associated paraspinal abscess. Cultures from the surgical evacuation of the paraspinal abscess yielded no pathogen growth and she was therefore treated with empiric antibacterial therapy. Two weeks after her initial hospital discharge she represented with severe back pain and radiologic evidence of progressive disease in her lumbar spine. Two additional vertebral biopsies were required during her first 2 weeks of admission. MAC eventually grew from culture 14 days after collection. She was treated with ethambutol and rifampin and her symptoms resolved in 2 weeks, though therapy was continued for 12 months.

CONCLUSIONS

MAC is an unusual cause of vertebral osteomyelitis in patients with AIDS, but is exceedingly rare in those without severe immune compromise. Despite its rarity, it must be considered in cases of vertebral osteomyelitis that do not respond to empiric antibiotic therapy. Multiple biopsies may be necessary to obtain a diagnosis and avoid destructive infectious complications of an untreated infection.

An Apparent Deficiency of Lymphatic Capillaries in the Islets of Langerhans in the Human Pancreas

The lymphatic system is crucial for efficient immune surveillance and for the maintenance of a physiological pressure in the interstitial space. Even so, almost no information is available concerning the lymph drainage of the islets of Langerhans in the human pancreas. Immunohistochemical staining allowed us to distinguish lymphatic capillaries from blood capillaries. Almost no lymphatic capillaries were found within the islets in pancreatic biopsy specimens from subjects without diabetes or from subjects with type 1 or type 2 diabetes. Lymphatic capillaries were, however, found at the islet-exocrine interface, frequently located along blood capillaries and other fibrotic structures within or close to the islet capsule. Lymphatic capillaries were regularly found in the exocrine pancreas, with small lymphatic vessels located close to and around acini. Larger collecting lymphatic vessels were located in fibrotic septa between the exocrine lobules and adjacent to the ductal system of the pancreas. In summary, we report a pronounced deficiency of lymphatic capillaries in human islets, a finding with implications for immune surveillance and the regulation of interstitial fluid transport in the endocrine pancreas as well as for the pathophysiology of both type 1 and type 2 diabetes.

Categorization of and comments on isomorphic and isotopic skin reactions

Locus minoris resistentiae (lmr) can be defined as a site of the body that offers lesser resistance than the rest of the body to the onset of disease. The well-known Köbner phenomenon is itself a clear example of lmr in dermatology. The new term locus maioris resistentiae (LMR), a site of the body that offers greater resistance than the rest of the body to the onset of disease, defines the opposite condition. Renbök phenomenon (reverse Köbner's isomorphic response) typically represents an example of LMR.

Ruocco's immunocompromised cutaneous district

The concept of 'locus minoris resistentiae' (lmr) is an old but still effective way of thinking in Medicine. In Dermatology, there are many reports of privileged localization of cutaneous diseases on injured skin, which therefore represents a typical condition of lmr. Lately the innovative concept of immunocompromised cutaneous district (ICD) has been introduced to explain why a previously injured cutaneous site may become in time a privileged location for the outbreak of opportunistic infections, tumors, and immune reactions. An ample documentation of multifarious disorders (infectious, neoplastic, immune) appearing in ICDs was delineated by Ruocco et al. in 2009. These cases were grouped according to the clinical settings responsible for the local immune imbalance: regional chronic lymphedema; herpes-infected sites, which feature the well-known Wolf's isotopic response; and otherwise damaged areas, comprising sites of vaccination, ionizing or UV radiation, thermal burns, and traumas. In the following five years, what was a "novel" pathogenic concept has been extended to an enlarging variety of clinical conditions. This paper focuses on ICD and the expanding spectrum of this now established pathogenic concept.