I just finished reading the article by Malyz et al in the May 2016 issue of JAAD (Cutaneous involvement of myeloma [MM]: A case series with clinicopathologic correlation).
They found that direct cutaneous involvement is rare (13 of 675 patients, 1.9%). Even though we need to differentiate it from other conditions such as a primary extramedullary plasmacytoma or primary cutaneous marginal zone lymphoma, no clinician will miss these lesions. The prognosis is poor.
I was wondering about the other end of the spectrum. I routinely check an SPEP in my standard idiopathic pruritus work-up. I’m not sure why I do – it is a matter of habit by now. I decided to look into the literature and there is precious little written about the topic.
I found a French article (Afifi Y, et al. Pruritus sine materia: a prospective study of 95 patients with idiopathic pruritus. Rev Med Interne 2004; 25: 490-3. The following were their results and conclusions.
“Ninety-five patients included (54 men, 41 women) of 55.5 years average age +/-18.1. In 24 patients, traditional hospitalisation with one average duration of eight days stay +/-3.15 was necessary. In 38 cases (40%), a systemic cause was found. The main conditions were: toxocariasis (8 cases), hematologic diseases (7 cases), chronic renal failure (6 cases), hypothyroidism (5 cases) and iron deficiency (5 cases). A neoplasm was found in eight cases (8,42%): seven hematologic malignancy (3 myeloma, 2 Hodgkin’s diseases, 2 myeloproliferative syndromes) and one solid cancer (pulmonary adenocarcinoma).
A systemic aetiology was observed in 38 cases (40%). The toxocariasis an underestimated disease comes at the first place. The pruritus sine materia can hide an hematologic malignancy.”
Admittedly, I do not get stool for ova and parasites for idiopathic pruritus (maybe I should!). Although it still seems like a long-shot to diagnose myeloma, I think I’ll still check an SPEP with my routine evaluation (CBC, TSH, chemistry profile and chest X-ray).
What is your take on this?