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.

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.

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.

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.

Type 1 diabetes

Skin lymphoma

Primary cutaneous B-cell lymphoma, leg-type

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