Case 409 -- A man in his 80s with multiple cutaneous nodules

Contributed by Sourav Ray, MD
Published on line in December, 2004


82 year old male presents with multiple cutaneous nodules over the chest and upper back which were removed and subsequently evaluated by a dermatopathologist. The skin lesions show dermal aggregates of pale epithelioid cells with occasional spindled morphology associated with moderate numbers of eosinophils.

A few weeks later the patient developed lethargy and presented to clinic. Routine laboratory testing including peripheral blood smear revealed:

Bone marrow biopsy was indicated to evaluate the leukoerythroblastosis with neutrophilia, monocytosis, slight anemia, and thrombocytopenia (see Image of Peripheral Blood).

Interestingly, it was also noted that the patient had a monoclonal IgM kappa in the serum of low concentration and unknown significance (MGUS).

Aspirate smears revealed trilineage hematopoiesis with focal aggregates of hypergranulated small to intermediate-sized cells with some having round centralized nuclei (Figure 1), some with markedly spindled morphology and loss of granularity (Figure 2), and some larger forms with clefted or bi-lobed nuclei (Figure 3).

Low power examination of the bone marrow showed it to be markedly (>90% cellular) with some hint of bony remodeling (Figure 4). Changes of osteosclerosis and bony remodeling were confirmed at higher power (Figure 5) and also a myeloid predominance with aggregates of pale epithelioid cells were noted(Figure 6).

Immunohistochemical stains were performed to better assess the abnormal infiltrate of pale epithelioid cells. Both tryptase and CD117 were strongly positive in multifocal aggregates of cells dispersed widely throughout the marrow space in clusters with >15 cells (Figures 7 and 8). Furthermore, these aggregates were strongly positive for CD25 and had scattered positivity for CD2 (Figures 9 and 10).

Reticulin stain performed on the marrow showed focally modest increases in reticulin fibrosis (Figure 11). Interestingly, the differential count suggested a mild increase in plasma cells and kappa immunostain revealed aggregates of plasma cells in excess of lambda immunostain in keeping with the patient's reported MGUS (Figure 12).


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