Furthermore, it is of utmost importance to address the patient’s axillary lymphadenopathy. Depending on the size and localization of the enlarged lymph nodes, different diagnoses should be considered. Various sonographic criteria are available to distinguish benign from malignant lymphadenopathy [
1,
2]. Usually, lymphadenopathy is classified as benign if lymph nodes have a diameter <1 cm and infectious and systemic diseases can be excluded. Lymph nodes with a diameter >2 cm often suggest malignancy; however, regardless of the size, the underlying cause of a progression in size of lymph nodes should always be investigated.
In summary, the described symptoms and findings strongly suggest the diagnosis of polyarteritis nodosa. These include (1) lymphadenopathy, (2) swollen feet, which occur in 80% of affected patients, and (3) fever, which is observed in 25–30% of cases. Furthermore, the prompt positive response to corticosteroids described in this case is typical for polyarteritis nodosa [
3] as are normal immune parameters, such as ANCAs, also observed in this patient [
4]. Approximately 50% of patients with polyarteritis nodosa present with livedo reticulatis, which, however, is difficult to diagnose in people with dark skin. On the other hand, the histopathological finding of vasculitis in this case does not strongly suggest polyarteritis nodosa, which is defined as necrotizing arteritis not associated with ANCAs of medium or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries or venules [
5]. Additionally, no organ is documented to be involved, which is also atypical for polyarteritis nodosa. Thus, other causes for lymphadenopathy and bullous skin rash in relation to rheumatological and infectious diseases have to be considered (Table
1). Although systemic lupus erythematosus (SLE) may present with negative serology (as observed in the discussed patient), the course of the disease in this case does not suggest SLE. Behcet’s disease can also be excluded because this disease does not occur in black people [
6] and with negative radiograph, CT and MRI, there are no indications for a granulomatous disease such as Wegener’s granulomatosis or lymphomatoid granulomatosis. Although serology was negative for various infections, at this point infection with
Mycobacterium tuberculosis cannot be ruled out. In my experience this infection can present with a wide range of symptoms. Other diseases (Table
1) that might cause lymphadenopathy and skin rash include inflammatory bowel disease (IBD). Both are typical symptoms in IBD and in some cases they present many years before intestinal manifestations of the disease. Cutaneous symptoms in IBD include vulvoperineal Crohn’s disease, genital lymphedema, lymphangioma circumscripta, orofacial granulomatosis, erythema nodosum, pyoderma gangrenosum, peristomal pyoderma gangrenosum, pyostomatitis vegetans, oral aphthous ulcers, Sweet’s syndrome, leukocytoclastic vasculitis, cutaneous polyarteritis nodosa and epidermolysis bullosa acquisita [
7]. Several cases of cutaneous polyarteritis nodosa in Crohn’s disease have been described [
7‐
9] and may also be suspected here. It should also be considered that cutaneous polyarteritis nodosa can be induced by
Mycobacterium tuberculosis [
10]. This limits our patient’s diagnosis to IBD, most likely Crohn’s disease, or mycobacterial infection. To finally establish the right diagnosis in this case I would propose tests for tuberculosis including an interferon-gamma release assay (IGRA), imaging studies of the abdomen and biopsy of an axillary lymph node. Since the axillary lymph nodes with a diameter up to approximately 4 cm are highly pathological, I strongly suspect tuberculosis in this patient.
Table 1
Causes for lymphadenopathy combined with a skin rash as described in the patient
Rheumatological diseases
|
Systemic lupus erythematosus Inflammatory bowel disease Behcet’s syndrome Polyarteritis nodosa Wegener’s granulomatosis Lymphomatoid granulomatosis | Systemic lupus erythematosus Inflammatory bowel disease Behcet’s disease Neutrophilic dermatoses Wegener’s granulomatosis Kawasaki disease |
Infections
|
Neisserial infections Subacute bacterial endocarditis Syphilis Fungal infections Mycobacterial infections | Neisserial infections Lyme disease Viral infections |