Cutaneous lymphosarcoma

From Felipedia

Cutaneous lymphosarcoma on the nasal bridge of a Domestic shorthair cat

Cutaneous lymphosarcoma on the mid-back region of a Persian cat

Cutaneous lymphosarcoma on the perineal region of a Persian cat

Cutaneous lymphoma on a 14-year-old domestic shorthair cat. Left front leg had already been amputated 12 months earlier for a similar tumour. Cat responded in the short-term to chlorambucil and prednisolone therapy. Courtesy of Dr Jim Euclid

Same cat as above

Although cutaneous neoplasia is common in cats^[1], cutaneous lymphoma is relatively uncommon. Cutaneous lymphoma is usually seen in older FeLV-negative cats. However, there may be a link between FeLV and cutaneous lymphoma because FeLV provirus has been isolated from neoplastic cutaneous cells^[2].

Cutaneous lymphoma can present as either a solitary lesion or generalized skin disease^[3] and can manifest as either chronic pruritic exfoliative skin disease or chronic inflammatory disease.

Two forms of cutaneous lymphoma have been described in cats: epitheliotropic and nonepitheliotropic. Epitheliotropic cutaneous lymphosarcoma can be categorized as three forms: mycosis fungoides, Sezary syndrome, or pagetoid reticulosis. Of these, mycosis fungoides is the most common type of epitheliotropic lymphosarcoma diagnosed in cats^[4].

Mycosis fungoides is a nonleukemic variant of cutaneous lymphosarcoma that occurs occasionally in dogs but rarely in cats. It is characterized histologically by epitheliotropic atypical lymphocytes, minimal spongiosis, and Pautrier's microabcesses (a discrete accumulation of neoplastic cells in the epidermis), which are characteristic histologic features of mycosis fungoides.

Sezary syndrome or Sezary-like disease has been reported in cats. It is characterized by the presence of cutaneous lymphosarcoma (generalized, exfoliative erythroderma, and lymphadenopmegaly) plus a leukemia. Pruritis is common. Histologic evaluation of skin lesions is consistent with that of mycosis fungoides, and the circulating neoplastic lymphocytes are large cells with convoluted, hyperchromatic nuclei and a high nuclear:cytoplasmic ratio that are known as Sezary cells.

Pagetoid reticulosis can resemble mycosis fungoides and Sezary syndrome histologically, because a monomorphous population of neoplastic lymphoid cells infiltrates the epidermis. Clinically, it appears to take a relatively benign course as a solitary plaque of chronic duration. Histologic examination of the ß-cell nonepitheliotropic form of cutaneous lymphosarcoma reveals lymphocytes located deeper in the dermis, with sparing of the papillary dermis and epidermis. The malignant lymphocytes are characterized as well-differentiated, poorly differentiated, undifferentiated, or large cell. Since T-cell lymphosarcoma can also appear as a nonepitheliotropic form, the lack of epidermal infiltration by lymphocytes is not by itself a useful criterion in defining ß-cell or T-cell forms of this disorder. Immunohistochemistry plus routine histologic assessment can be used to distinguish B-cell from T-cell lymphosarcoma. Clinical lesions are usually discrete solitary or multifocal nodules, sometimes with acute onset and rapid progression^[5].

Clinical signs

Cutaneous lymphosarcoma is characterized by infiltration of any area of the skin by neoplastic lymphocytes. It can occur as the primary form of lymphosarcoma, or it may be disseminated from or to other areas. It may occur as single or multifocal lesions on the skin. Cutaneous lymphosarcoma can affect any skin surface, but it often will exhibit mucocutaneous and oral cavity involvement.

General clinical signs include nodules, plaques, pustules, ulcers, erythroderma, depigmentation, or exfoliative dermatitis. The size of involved areas ranges from small (few millimeters) to large nodules or plaques (centimeters in diameter). Small animals initially may present with lesions of coalescing, erythematous patches with alopecia and scale on the head and face, that progress to the trunk. This form then progresses to circular then irregular erythemic plaques, some with central ulceration and dry crusts on mucocutaneous junctions. The plaque form is more common in cats than in dogs. Pruritis is variable with the patch and plaque forms, but cats tend to be more pruritic than dogs and may show more self-trauma and ulceration. Both the patch and plaque forms can regress and reappear at a later date or progress rapidly to a more aggressive form^[6].

Variably sized, painless nodules (solitary or multiple) can appear as firm, elevated, dark red, shiny, scaly, or ulcerated lesions with serous exudate oozing onto the skin surface. This exudate tends to trap keratin and form a crust on top of the nodule. If the crust is removed, the skin underneath may be hemorrhagic and hyperemic. The combination of ulcerative skin and crust can lead to areas of matted hair with a foul odor. Less pruritis is usually seen with this stage than with previous stages, although secondary bacterial infection' can cause pruritis. Progression to lymph nodes or other organs can occur.

Hematologic changes associated with cutaneous lymphosarcoma are varied and include anemia, lymphopenia, lymphocytosis, neutrophilia and leukemia. Hepatic and renal changes may be noted. Hypercalcemia is rare but tends to occur when only the skin is affected (no lymph node or solid organ metastasis). A monoclonal gammopathy (IgG) was reported in one dog with cutaneous lymphosarcoma.

Diagnosis and staging

The diagnosis of cutaneous lymphosarcoma is dependent on biopsy. Although a diagnosis of cutaneous lymphosarcoma may be established with a fineneedle aspiration cytology, histopathology is advised in order to fully characterize the nature of the tumor. With the availability and use of immunohistochemis try for cell markers, every effort should be made to identify the tumor as T or B cell origin. Staging for cutaneous lymphosarcoma is the same as for other forms of lymphosarcoma^[7].

Cutaneous lymphosarcoma need to be distinguished in a differential diagnosis with cutaneous haemangiosarcoma.

Treatment

Treatment of cutaneous lymphosarcoma is often frustrating. Many treatments must be considered palliative, but some relief from clinical signs can be be offered. For example, regular bathing with sulfur-based shampoos may increase patient comfort and appearance, but has no effect on the primary disease. Prednisone can be used to successfully control persistent pruritis (doses ranging from 0.15-1.8 mg/kg every 24-48 hrs), but may have no appreciable effect on survival.

Radiation therapy has been used for solitary or multifocal lesions. One dog with mycosis fungoides was reported responsive to orthovoltage radiation. Palliative radiation therapy of dogs with mycosis fungoides can be rewarding, and ulcerated lesions may heal and regress.

The best survival times for cutaneous lymphosarcoma are usually the result of treatment with combination chemotherapy protocols, especially if doxorubicin is a part of the protocol. Remission of 46 days was reported in one dog with epitheliotropic cutaneous lymphosarcoma treated with chlorambucil and prednisone, while a remission of 304 days was reported for another dog treated with doxorubicin, vincristine, and prednisone.

References

1. ↑ Fox LE (1995) Feline cutaneous and subcutaneous neoplasms. Vet Clin North Am Small Anim Pract 25(4):961-979
2. ↑ Ettinger SN (2003) Principles of treatment for feline lymphoma. Clin Tech Small Anim Pract 18(2):98-102
3. ↑ Tobey JC, Houston DM, Breur GJ, et al (1994) Cutaneous T-cell lymphoma in a cat. JAVMA 204(4):606-609
4. ↑ Baker JL, Scott DW (1989) Mycosis fungoides in two cats. JAAHA 25:97-101
5. ↑ Schick RO, Murphy GF, Goldschmidt MH (1993) Cutaneous lymphosarcoma and leukemia in a cat. JAVMA 203(8):1155-1158
6. ↑ Day MJ, Kyaw-Tanner M, Silkstone MA, et al (1999) T-cell-rich B-cell lymphoma in the cat. J Comp Pathol 120(2):155-167
7. ↑ Fox LE (1995) Feline cutaneous and subcutaneous neoplasms. Vet Clin North Am Small Anim Pract 25(4):961-979