Multiple Myeloma with Cutaneous Deposits as Rare Lymphoplasmacytoid Cells.

Sir,

Cutaneous involvement in multiple myeloma (MM) occurs in 2% of myeloma cases[1] and has most commonly been reported to involve the trunk, abdomen, scalp, face, neck, lower extremities followed by upper extremities.[2]

The specific cutaneous lesions related to MM are the secondary plasmocytomas, which occur commonly by direct extension to the skin, from underlying bone lesions, or rarely by hematogenic spread. The latter is represented by subcutaneous or intradermal violaceous nodules which occur in advanced myeloma.[3]

Though non-specific lesions like localized cutaneous mucinosis[4] and cutaneous vasculitis[5] have been reported as presenting feature of MM from India, we are reporting a specific case of MM with cutaneous deposits as rare lymphoplasmacytoid cells.

A 64-year-old female, a diagnosed case of IgG MM on treatment with biological and chemotherapy followed by palliative radiotherapy since 3 years, presented to our OPD with multiple nodules over the left lower limb since 1 month. On examination, the patient was anemic with left cervical and bilateral inguinal lymphadenopathy and pedal edema of the left leg. Multiple hard, warm, reddish blue nodules forming a tumorous growth were present on anterior aspect of the left leg, left thigh, abdomen, and back. Central necrosis was noted in few nodules [Figure 1].

Figure 1

Erythematous hard tender nodules over left leg (a), after radiotherapy (b), left abdomen and thigh with central necrosis (c) and left flank (d)

Sagittal MRI of the whole spine, MRI pelvis and bone scintigraphy [Figure 2] were suggestive of extensive lytic bone lesions with pathological fracture in the right proximal tibia. Serum electrophoresis showed prominent M band in the gamma region (IgG) [Figure 3]. A bone marrow study reported 16% plasma cells with occasional Mott cells. Investigations revealed pancytopenia, raised serum blood urea, creatinine and ESR with a lowered serum potassium and calcium levels.

Figure 2

Tc99 bone scintigraphy showing multiple areas of increased uptake notably in left maxilla, left clavicle, right sacroiliac joint, left acetabulum and bilateral proximal tibia

Figure 3

Serum electrophoretic pattern of patient showing prominent M band (arrow) in gamma light chain region. The table below shows individual fractions

A deep biopsy of a nodule showed an unencapsulated neoplasm in the dermis and subcutaneous tissue with sheets and groups of large oval cells, vesicular nuclei, prominent nucleoli with no obvious glandular or plasma cell differentiation. Immunohistochemistry revealed focal strong positivity for CD138 and CD45, and focal strong membranous positivity for an epithelial membrane antigen (EMA) [Figure 4]. Thus, a diagnosis of secondary deposits (lymphoplasmacytoid cells) of MM was made.

Figure 4

(a) Histopathology from nodule in left leg (HandE, ×4); Strong immunohistochemical (IHC) staining positivity (×40) for (b) CD138 (black arrow), (c) CD45 (yellow arrow) and (d) EMA (pink arrow)

Localized lesions were treated with radiotherapy and palliative chemotherapy was planned later. After about 2 months of onset of skin lesions, the patient succumbed to the disease due to multiorgan failure.

MM occurs predominantly in the 40 to 70 year group with male predominance. Cutaneous involvement by MM is not immunoglobulin specific, though IgG (our case too) as the most frequent subtype and IgD with aggressive biological behavior have been described.[2]

Histopathologically, the lesions of MM involving the skin show two patterns: Nodular and diffuse interstitial.[2] In specific lesions, diffuse infiltration of the dermis by atypical plasma cells or lymphoplasmacytoid cells is present. Neoplastic plasma cells can be stained with CD38 (white blood cells) and CD138, and they express monotypic immunoglobulins. Russel bodies (intracytoplasmic eosinophilic inclusions), Mott cells (grape-like clusters) and Dutcher bodies (intranuclear eosinophilic inclusions) due to immunoglobulin or glycoprotein accumulations can be observed.[6]

Lymphoplasmacytoid cell stains positively for both plasma cell (CD138 and CD38) and lymphocyte (CD45) markers emphasizing its common lineage and cell of origin. CD138 (as in our case) is not present in other hematopoietic cells or endothelial cells and its expression is consistent with myeloma metastasis and a marker for prognosis.[2]

Localized cutaneous plasmacytomas can be treated with radiotherapy while those extensive may warrant palliative chemotherapy.