Pigmented Purpuric Dermatoses

Am J Clin Pathol. 2007 Aug;128(2):218-29. Abstract quote

The categorization of pigmented purpuric dermatosis (PPD) as a form of cutaneous lymphoid dyscrasia has been suggested. Phenotypic and molecular studies were done on 43 patients with PPD. The molecular studies used a capillary gel electrophoresis T-cell receptor beta multiplex polymerase chain reaction assay.

There were 2 principal categories: polyclonal PPD represented by 22 cases and monoclonal variants comprising 21 cases. Monoclonal cases had extensive skin lesions. An identical restricted T-cell repertoire independent of time and location was observed. Approximately 40% of the monoclonal cases had clinical and pathologic features of mycosis fungoides (MF). In the polyclonal variant, disease outside the lower extremities was uncommon; there were no patients with MF. Striking reductions in CD7 and CD62L were seen in both groups.

PPD is a form of cutaneous T-cell lymphoid dyscrasia, based on the frequency of monoclonality, the preservation of persistent T-cell clonotypes, and extent of pan-T-cell marker loss. Stratification of lesions of PPD according to the molecular profile may be of significant value prognostically and influence therapeutic intervention.

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Progressive pigmented purpura
INCIDENCE	Common
AGE RANGE-MEDIAN	Younger adults

DISEASE ASSOCIATIONS	CHARACTERIZATION
Isolated reports following exposure	Dyes Thiamine treatment Carbromal Meporbamate Diuretics Ampicillin NSAIDs Acetominophen Herbal remedies

PATHOGENESIS	CHARACTERIZATION
GENERAL	Several mechanisms have been proposed but no single theory has explained all of the changes Delayed humoral immunity Delayed hypersensitivity Perforater vein incompetence
T-CELL LYMPHOID DYSCRASIA
Pigmented purpuric dermatosis: classification by phenotypic and molecular profiles. Magro CM, Schaefer JT, Crowson AN, Li J, Morrison C. Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University New York Presbyterian Hospital-Cornell Campus, New York, NY 10021, USA.	Am J Clin Pathol. 2007 Aug;128(2):218-29. Abstract quote The categorization of pigmented purpuric dermatosis (PPD) as a form of cutaneous lymphoid dyscrasia has been suggested. Phenotypic and molecular studies were done on 43 patients with PPD. The molecular studies used a capillary gel electrophoresis T-cell receptor beta multiplex polymerase chain reaction assay. There were 2 principal categories: polyclonal PPD represented by 22 cases and monoclonal variants comprising 21 cases. Monoclonal cases had extensive skin lesions. An identical restricted T-cell repertoire independent of time and location was observed. Approximately 40% of the monoclonal cases had clinical and pathologic features of mycosis fungoides (MF). In the polyclonal variant, disease outside the lower extremities was uncommon; there were no patients with MF. Striking reductions in CD7 and CD62L were seen in both groups. PPD is a form of cutaneous T-cell lymphoid dyscrasia, based on the frequency of monoclonality, the preservation of persistent T-cell clonotypes, and extent of pan-T-cell marker loss. Stratification of lesions of PPD according to the molecular profile may be of significant value prognostically and influence therapeutic intervention.

SPECIAL STAINS/ IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
CD4+	Majority of lymphocytes

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Mycosis fungoides	Rarely, MF may clinically and histologically resemble this disease