#dermpathJC May 2017:

Thursday, May 25th, 9pm EST

Article discussed: “Cutaneous Plasmacytosis: A Clinicopathologic Study of a Series of Cases and their Treatment Outcomes.”

Authors: Han X, Lee S, Tan S, Chong W, Ng S, Ooi M and Goh C.

American Journal of Dermatopathology, 2017.

Free access at: tinyurl.com/kq8vzdb  from MAY21 to JUNE21!

Special thanks to Dr Adrienne Jordan @JordanDermPath for providing the summary below.

Journal Club Summary:

Review of the article:

1. Cutaneous plasmayctosis presents clinically as reddish brown nodules on the trunk of adults; most common in Asians; chronic course (lesions present for 2-10 years)
a. Axilla is almost always involved
b. Elevated serum immunoglobulins (IgG most common)
c. Elevated Kappa and lambda free light chains, but Kappa to lambda ratio is preserved
2. Histology:
a. Perivascular dermal infiltrate of mature polyclonal plasma cells; no atypia
b. Mast cells are increased (some are degranulating)
c. Increased basal melanin pigment
d. Vascular proliferation common
e. Psoriasiform epidermal hyperplasia
f. Lymphoid follicles may be present
g. HHV8 and EBV negative
3. Treatment:
a. Mask bath PUVA
b. Oral antibiotics
c. Topical and intralesional steroids
d. Topical tacrolimus
4. Poor prognostic factors:
a. IgG > 5000 mg/mL
b. High plasma cell count in bone marrow
5. Differential diagnosis
a. Secondary syphilis: Spirochetes seen on Warthin Starry stain or IHC
b. Rosai Dorfman: Infiltrate also has abundant histiocytes and emperipolesis
c. Plasmacytoma: monoclonality and plasma cell atypia
d. MZBCL: very difficult distinction; monoclonality (specifically performing heavy chain gene rearrangement studies) may be helpful

Review of Journal Club Discussion:
1. It was hypothesized that since IL-6 is increased in patients with CP and IL-6 receptors are localized on melanin this explains the increased basal melanin pigmentation
2. Castlemans disease and plasma cell granuloma were added to the list of differential diagnoses
3. Although not reported in this series, other articles have commented on perineural plasma cells being prominent in CP
4. Although other papers have described an increased IgG4, participants agreed that CP is not part of the IgG4 diseases as sclerosis is not generally a feature of CP as it is in the IgG4 diseases
a. If sclerosis is present, one should consider a plasma cell granuloma
5. Very nice chart provided to help differentiate plasma cell infiltrates in the skin: