Shoulder Pain in a Weight-lifting Adolescent Athlete: A Zoonotic Etiology

Introduction More than 50% of high school students participate in a sport (1), which increases their risk of injury. Musculoskeletal pain is the second most common complaint in the adolescent athlete (2). It is more likely to occur in training or competition (63.8%), usually from indirect or overuse causes (68.8%). This can cause discontinuation of the sport (3). It has been reported that 43.5% of adolescent athletes currently complain of pain and 54.3% have claimed it within the last year (3). Skeletal immaturity increases susceptibility to pain and injury from lack of rest, training overload, and poor technique (2,3). Maladaptive bone and soft tissue changes from pain affect function and increase risk for further injury, correlating to longer recovery times. There are nearly a million estimated weight training injury visits per year in emergency departments, with up to 75% being acute injuries (4). Shoulder injuries are the fifth most common injury and make up 8% of all injuries sustained by high school athletes (1). Resistance injuries, in which free weights account for 90%, can occur from technical errors (31%), fatigue and overloading (81%), and dropping weights (65%) (4). The lift phase of the bench press causes 47% to 70% of these injuries. The pectoralis major-powered forced abduction of the arm puts the trainee at risk for pectoralis tendon ruptures, proximal biceps tendon ruptures, capsulolabral injuries, and other shoulder pain (4). Long-term physical consequences of these injuries are instability and joint degeneration (1). Recovery, however, involves an emotional meshwork of complex psychosocial factors, such as fear avoidance, catastrophic thinking, maladaptive coping, and avoidance behaviors that all prolong recovery (5). Determining appropriate diagnosis decreases these issues and aids in recovery. To aid in determining appropriate diagnosis, a systematic approach to shoulder pain is essential. Initially, it is important to obtain a thorough history of the pain. Chronicity of the pain is important. If acute, then questions should focus on timing and mechanism of injury (6). If chronic, then medical, family, occupational, and social histories should be considered when determining diagnosis. Physical examination includes inspection of affected area, palpation, range of motion testing, and any dynamic examinations deemed necessary. The history combined with physical examination findings should lead to diagnosis or if further testing is indicated, such as plain radiographs, magnetic resonance imaging (MRI), or ultrasound. By following this process, musculoskeletal shoulder pain should be easily diagnosed. The following report details an unexpected and rarely reported zoonotic cause of shoulder pain in a weightlifting high school athlete and was discovered utilizing this method. Case Presentation An 18-year-old male athlete presented to an outpatient clinic with a 5-d history of sharp pain and popping sensation in the left axilla while preforming a bench press, resulting in a palpable lump. The pain worsened with overhead movements and was refractory to ice and heat. He did note associated chills and night sweats, but no fever, headache, dyspnea, nausea, or vomiting. On examination, his left upper extremity had full range of motion. Upon palpation, there was a mass noted just under the pec in anterior axilla. Neer (assessing for impingement), Hawkins (assessing for impingement), Drop Arm (assessing for supraspinatus tendonitis or tear), Yergason's (assessing for biceps tendonitis or tear), O'Brien's (assessing for labral tear), and external rotation tests were all negative (7). His left upper extremity also was neurovascularly intact distally. Out of concern for muscle tear and subsequent need for surgical correction, MRI was ordered, which noted a 4.3-cm× 2.0-cm× 2.1-cm cluster of axillary lymph nodes, which extended into the lateral infraclavicular area (Fig. 1). The patient was admitted to the hospital for evaluation by pediatric oncology. Biopsies taken showed reactive lymph nodes. Serology was obtained (Fig. 2), demonstrating both Bartonella hensellae IgM (1:800) and IgG (1:2560), and he was diagnosed with Cat Scratch Disease (CSD). Further investigation uncovered recent contact with a household feline. Resolution of the lymphadenopathy and the shoulder pain occurred after a course of azithromycin.Figure 1: MRI findings of the shoulder demonstrating lymphadenopathy (white arrow): (A) Axial, (B) Coronal, (C) Sagittal.Figure 2: Patient serology results denoting an old EBV infection and more acute Bartonella infection. CMV, cytomegalovirus; EBV, Epstein Barr virus; IgM, immunoglobulin M, IgG, immunoglobulin G.Discussion A systematic approach to shoulder pain continues to be essential when diagnosis due to inflammatory or infectious etiologies is evident. The initial history and physical seemed congruent with musculoskeletal injury, such as pectoralis minor and/or coracobrachialis strain/tear as suspected in this case. When the MRI revealed axillary lymphadenopathy, further investigation beyond musculoskeletal etiologies needed be considered. Included in the differential were skin infections, lymphomas, leukemia, soft tissue/Kaposi sarcoma, skin neoplasms, breast adenocarcinomas, tularemia, sporotrichosis, sarcoidosis, syphilis, and CSD (7). With lymphadenopathy present, history should now focus on infectious contacts, medications, recent travel, environmental and occupational exposures, and both sexual and family history. Physical examination should detail an overall lymphatic examination with regional emphasis directed by the lymphatic drainage patterns of the affected lymph nodes (7). Further testing may include additional imaging with point of care ultrasound, serology targeted by history, and biopsy when indicated. CSD is an infectious process predominately caused by Bartonella henselae; a thin-walled Gram-negative bacteria (8) that is most commonly transmitted to humans via cats (9–11). It was first recognized in 1931 in France (8,12), but it was not until 1988 when DJ Wear could isolate the pathogen (8,13). Incidence of CSD seems driven by cat ownership, as 90% of affected patients report some contact with felines (8,14–16). While cats are the most common reservoir, other mammals can be vectors (17,18). The bacteria reside in feline erythrocytes, with fleas and ticks spreading the bacteria between carriers (9,14). Between 33% and 50% of cats may be bacteremic, but do not appear ill (8,12,13,17,19). Kittens are more likely bacteremic (8,12,15) and are involved in 15 times the clinical cases (9). Household contacts are not automatically affected because family coinfection is seen in less than 5% of cases (8,13). Despite predominately being a pediatric issue (8,9,18,20,21), with 87% of cases occurring in those younger than 18 years (10,13,22), it has been reported in patients aged 84 years (13,22) without gender difference (22). CSD in America is more commonly seen in temperate to warm and humid climates (8,9,14,17). There is a seasonality to the incidence, as it predominately occurs in fall to winter months (8,13,22). Up to 24,000 people are affected annually (14,15,20) with 10% (20,21) to 24% (18) requiring hospitalization, creating a national inpatient medical burden of US $5.2 million and US $6.9 million outpatient (22). CSD typically presents with ipsilateral regional lymphadenopathy, preceded 3 to 10 d (8,11–13,17) by a cutaneous inoculation lesion from any break in the skin (12,13,15,17,18,21). The oft neglected cutaneous lesion (15), occurs 61% to 92% of the time. It begins as a 2- to 5-mm red macule (8) that becomes papular before forming a vesicle containing opaque liquid (14) and eventually a crusting scar (8,16). The hands and arms are the most likely inoculation site, having the most contact with cats (13). More than 80% of cases (14,16,17,20) experience lymphadenopathy, with tenderness, enlargement, and overlying erythema (13,16), but there can be asymptomatic exceptions (9). Predominately occurring in a singular node (65%) in the head, neck, or axilla, the adenopathy can be multifocal (30%) or generalized (5%) (8,20). It is usually self-limited, spontaneously resolving in 2 to 4 wk (11,18). However, the inflammation can proceed to granulomatous suppuration and central necrosis prior to resolving within 2 to 4 months (4,8,14,16–18,21). Constitutional symptoms, such as fever, nausea, vomiting, headache, malaise, anorexia, pharyngitis, and conjunctivitis, will accompany this course 30% to 60% of the time (8,15,17,21). The typical, self-limited presentation occurs in about 90% of cases (15,17,19,21). Atypical presentations (Table 1) occur when extranodal hematogenous spread of the organism occurs to distant organ systems (18) and are more likely in immunocompromised patients (9,14,20). Musculoskeletal involvement of CSD is rare (0.17% to 0.27%) (15,21) and usually involves discitis (17,18), arthritis (19), and nontoxic (13) appearing lytic osteomyelitis (8,11,15,18). These lytic osteomyelitis lesions are granulomatous and centrally necrotic (11,18). They can appear contralateral to the inciting inoculation, with the infection thought to spread through blood or lymph (11). Inflammatory markers can be moderately elevated (18), but most patients do not appear septic (13). In this report, a musculoskeletal injury was initially suspected based on the weight-lifting mechanism of injury and subsequent symptoms. Instead, the musculoskeletal pain was caused by abnormal tendinous movement over an enlarged lymph node from CSD. Table 1 - Atypical manifestations of cat scratch disease: these occur 10% of the time and represent distant effects within organ systems. Atypical Manifestations of Cat Scratch Disease Cardiac System Hematologic/Reticuloendothelial System Endocerditis Hemolytic anemia Mediastinal lymphadenitis Hepatosplenic lesions Pericardial effusion Hepatosplenomegally Nonthrombocytopenic purpura CNS System Peliosis hepatitis Encephalitis Thrombocytopenic purpura Encephalopathy Musculoskeletal System Focal nerve compression Arthritis/arthropathy Myelitis Discitis Paraplegia Myalgias Polyneuritis Osteolytic lesions Radiculopathy Osteomyeitis Ophthomologic System Dermatologic System Branch retinal artery ad venous occlusions Erythema nodosum Iritis Macular hole Infectious System Neuroretinitis Abscesses Optic neuropathy Bacillary angiomatosis Panuveitis Bacterial pelosis Papilitis Bacteremia Parinaud oculoglandular syndrome Cat scratch fever Retinal vasoproliferative lesions Fever of unknown origin Retinal white spots Vitral detachment GI System Pulmonary System Mesenteric lymphadenitis Pleural effusions Pneumonia Pulmonary nodules The diagnosis of CSD is based on five criteria: exposure to a feline, the presence of an inoculation site, regional lymphadenopathy, a positive cat-scratch skin test antigen response, and negative biopsy results to rule out other causes of lymphadenopathy (4,13,16,17). It is important to note that not all five criteria have to be evident to make the diagnosis. The antigenic skin test is performed in a similar manner as a tuberculin test, with an intradermal injection of 0.1 mL of CSD antigen on the forearm and examination for induration 72 h later. A positive result occurs with induration of 5 mm or greater. False-positive results are due to residual antigenicity from a past exposure. False negatives can occur with testing less than 1 wk after exposure (8). Because the antigen comes from human tissue, there is a theoretic risk of infectious organism transmission. The organism itself is difficult to isolate from the nonnecrotic lymph node suppuration. A Warthin-Starry silver impregnation and Brown-Hopps stain (4,8,16,17,20) are required to demonstrate the organism. PCR augmented serologic testing via indirect fluorescent assay or enzyme-linked immunosorbent assay are currently the best initial tests, but this also can have false positive results from a previous exposure (14). Because these forms of testing retain some error, treatment may be prudent without conclusive results. Imaging, whether ultrasound or MRI, is not very helpful in routine cases, although point-of-care ultrasound can identify lymph node, splenic, or hepatic involvement (10). In atypical cases, MRI may be helpful to demonstrate the extent of bony and soft tissue involvement (10,15,18). As lymph node enlargement is nonspecific, histological examination can be important to exclude other causes in the differential (Table 2). Biopsies, which can lead to fistulas, should be reserved for prolonged courses or unclear etiology. Results show a mixture of inflammatory reactions of caseating granulomas, microabscesses, and follicular hyperplasia with central suppurative necrosis (8). Table 2 - Details the differential diagnoses for cat scratch disease for the neck, axilla, and upper extremities. Differential Diagnosis for Cat Scratch Disease Infections Baceterial Anaerobic Brucella Tonsilopharyngitis, pyogenic (GABHS) Tularemia Fungal Mycobacterium Sarcoidosis Tuberculosis Protazoan Toxoplasmosis Viral Cytomegalovirus Epstein Barr virus Human immunodeficiency virus Inflammatory Pathology Juvenile rheumatoid arthritis Kawasaki Serum sickness Systemic lupus erythematosus Malignancies Lymphomas (Hodgkin's) Structural abnormalities Branchial cleft cysts Cystic hygromas As opposed to a cat bite, for which amoxicillin-clavulanic acid is the agent of choice, treatment with antibiotics for typical CSD is controversial because they do not shorten the course or decrease chance of suppuration (8,9,13,16,20,21). Antibiotics should be reserved for immunocompromised patients (12) or atypical presentations (14). Should one be considered, azithromycin is the antibiotic of choice (12,14,18), but rifampin, ciprofloxacin, bactrim, and gentamycin have all been shown effective (4,17). Symptomatic treatment is the mainstay (4), which includes analgesics, local heat, and limiting activity to prevent lymph node rupture (8,13). Aspiration (8,12,13,16,20) can have symptomatic, diagnostic, and therapeutic benefit (8,9,12), but should be reserved for unclear cases as fistula formation is possible (9). Likewise, surgical removal is reserved for problematic courses (8,12–14). There is no need to treat household contacts (8), but good handwashing hygiene of cuts and scratches is recommended (12). As the carrier status only occurs temporarily, there is no need to diagnose and/or dispose of pets (8,9,12). Despite recurrence in the affected individual being rare (4), preventative measures of notifying health care workers of new lesions, rashes, or lymphadenopathy is advisable. Conclusions Pain from musculoskeletal injuries occur in adolescent athletes regularly. These are routinely managed conservatively unless severe or refractory to treatment. When work-up fails to yield a musculoskeletal cause, the differential needs to widen. Presented here is an uncommon etiology of shoulder pain that underscores the importance of a systematic approach to musculoskeletal complaints in order to identify infectious and inflammatory causes. CSD predominately affects the lymph nodes of the upper extremities, axillary, and neck region and should be considered in unusual cases involving upper extremity lymphadenopathy.