Primary cutaneous B cell lymphoma, leg type presenting as a diabetic ulcer: A challenging diagnosis

Introduction: A crescent number of reports describe malignant dermal malignancies presenting as diabetic ulcers, such as melanoma, Kaposi's sarcoma, squamous cell carcinoma and cutaneous lymphoma. Methods: The authors reported the clinical and histopathological features of this challenging case of a PCBCL, leg type presenting as a foot ulcer to exemplify the diagnostic difficulties, mainly when, at the onset, this tumour exhibits uncharacteristic features. Case report: A 43 years-old male with a 10-year history of compensated type I diabetes developed an ulcerated 3 cm of diameter tumour on the lateral region of the right foot. This lesion had previously been biopsied and treated as a diabetic neuropathic ulcer elsewhere. Due to the appearance of intralesional necrosis associated with stable inflammation and diabetes laboratory parameters, the clinicians made a provisional clinical diagnosis of pyoderma gangrenosum and performed further two incisional biopsies. Histology showed a clear-cut PCBCL, leg type. Conclusions: Diabetic skin lesions, especially in older patients with persistent non-healing characteristics of pain and tenderness, must be carefully managed through the close correlation of clinical, imaging, and histological features. A correct diagnosis allows avoiding inadequate treatment, which would lead to severe consequences for these patients.