Page 417 - Problem-Based Feline Medicine

20 – THE CAT WITH ENLARGED LYMPH NODES 409

METASTATIC NEOPLASTIC Treatment
LYMPHADENOPATHY: MAST CELL TUMOR* See page 1075 (The Cat With Skin Lumps and Bumps).

Classical signs
● Firm cutaneous nodule (cutaneous form). METASTATIC NEOPLASTIC
● Marked splenomegaly (lymphoreticular LYMPHADENOPATHY: OTHER TUMORS*
form).
Classical signs
See main reference, page 1074 (The Cat With Skin
● Signs of primary tumor.
Lumps and Bumps).
● ± Local, regional or generalized
lymphadenopathy.
Clinical signs
See main reference, page 1067 (The Cat With Skin
Most primary cutaneous mast cell tumors present as Lumps and Bumps).
single, or less commonly, multiple dermal nodules
without other clinical signs.
● Histologically they may be classified as compact Clinical signs
mastocytic, diffuse mastocytic and histiocytic. The
The cat is usually presented for signs of the primary
average age of cats with mastocytic tumors is 10
tumor.
years, while the average age with histiocytic
tumors is 2.4 years. Occasionally the cat is presented because of local,
regional or rarely generalized lymphadenopathy.
Cutaneous mast cell tumors may infrequently metas-
tasize to local, regional and distant peripheral lymph Most metastatic neoplasia occurs in older cats.
nodes causing lymphadenopathy. This is most likely
with diffuse mastocytic tumors and tumors with
> four mitoses/ten high-power fields. Diagnosis
Cutaneous and lymphoreticular (splenic) mast cell Lymph node biopsy reveals hyperplasia and infiltration
tumors may occur together with variable involvement by carcinoma, uncommonly sarcoma, and rarely non-
of internal and peripheral lymph nodes. The average lymphoid, non-mast cell round cell tumors.
age of cats with lymphoreticular tumors is 10 years. ● Carcinomas include squamous cell carcinoma,
bronchogenic carcinoma, mammary carcinoma and
Diagnosis others.
● Sarcomas include fibrosarcoma, osteosarcoma and
Biopsy of the cutaneous mass and/or spleen reveals others.
numerous normal or atypical mast cells. ● Round cell tumors include plasma cell tumors,
myeloid leukemia, malignant histiocytosis and
Lymph node biopsy reveals hyperplasia and increased
melanoma.
numbers of mast cells.
If the cat is presented for lymphadenopathy, reviewing
the history and physical examination, and performing
Differential diagnosis
routine laboratory evaluation, and thoracic and
Other neoplasia, eosinophilic granuloma complex, abdominal radiographs and ultrasound examina-
chronic bacterial infections, fungal infections, and pro- tions, will help identify and stage the primary
tothecosis. tumor.
Differentiation is based on cytology, histology and Normal and enlarged regional lymph nodes should be
culture. biopsied as part of clinical staging of the cat with cancer.