Cutaneous manifestations of peripheral T-cell lymphoma, not otherwise specified: a case series highlighting the diagnostic challenges for this heterogeneous group.

Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) is a rare, heterogeneous group of nodal and extranodal mature T-cell lymphomas that do not correspond to any of the defined T-cell entities, according to the World Health Organization classification. Most cases present with late stage nodal disease; however extranodal involvement is common. Skin and subcutaneous involvement is reported in approximately 20% of cases. Little attention has been given to the highly variable skin manifestations in the literature. It is our experience that lesions can present in ways other than previously described nodular or tumourous lesions that often ulcerate. We present a case series from a large tertiary institution of seven cases of PTCL, NOS with skin involvement, highlighting the variable presentations and diagnostic challenges for this heterogeneous group.

Diagnosis of type I cryoglobulinaemia made through identifying crystals in the blood smear.

We report a case of type I cryoglobulinaemia in a 52-year-old man who presented with widespread cutaneous necrosis. The diagnosis could not be established early on, as repeated testing for cryoglobulin was negative despite a careful collection method. The diagnosis was made 1 year later, on an incidental full blood smear that revealed crystals, which is an uncommon way to diagnose this condition. We discuss the difficulties we faced in establishing the diagnosis and emphasise the need for repeat cryoglobulin testing in this clinical setting. In such cases, examination of a blood smear should be considered.