Histiocytoid Carcinoma of the Breast
Differential Diagnosis
- Lipid Rich Carcinoma
- Glycogen Rich Clear Cell Carcinoma
- Secretory Carcinoma
- Granular Cell Tumor
- Fat Necrosis, Inflammation, Histiocytic Infiltration
- Apocrine Carcinoma
- Lobular Carcinoma
| Lipid Rich Carcinoma | Histiocytoid Carcinoma |
|---|---|
| Lipid stain positive | Lipid stain negative |
| GCDFP15 variable to weak | GCDFP15 strong positive |
| Mucin negative | Mucin positive intracytoplasmic lumens or granular cytoplasm |
| May have any grade cytology | Low grade cytology |
| Lacks intracytoplasmic lumens | May have intracytoplasmic lumens |
| Glycogen Rich Clear Cell Carcinoma | Histiocytoid Carcinoma |
|---|---|
| Clear cytoplasm | Finely vacuolated cytoplasm |
| PAS shows abundant glycogen | PAS shows granular mucin |
| GCDFP15 variable | GCDFP15 strong positive |
| Histiocytoid Carcinoma | Secretory Carcinoma |
|---|---|
| All reported cases >40 years | Most cases <30 years |
| Scant or granular mucin | Abundant cytoplasmic mucin |
| GCDFP15 strong positive | GCDFP15 variable |
| Aggressive behavior | Excellent prognosis |
| Histiocytoid Carcinoma | Granular Cell Tumor |
|---|---|
| Keratin, EMA positive | Keratin, EMA negative |
| GCDFP15 positive | GCDFP15 negative |
| S100 negative or trace | S100 positive |
| Histiocytoid Carcinoma | Fat Necrosis, Inflammation, Histiocytic Infiltrations |
|---|---|
| Keratin, EMA positive | Keratin, EMA negative |
| GCDFP15 positive | GCDFP15 negative |
| CD68, HAM56 negative | CD68, HAM56 positive |
| Low grade atypia | Completely bland nuclei |
| Granular mucin positivity | Mucin stains negative |
| Histiocytoid Carcinoma | Apocrine Carcinoma of the Breast |
|---|---|
| Amphophilic to weakly eosinophilic cytoplasm | Intensely eosinophlic cytoplasm |
| Cytoplasm vacuolated, occasionally granular | Cytoplasm granular |
| Indistince cytoplasmic borders | Sharp cytoplasmic borders |
| Small nuclei and nucleoli | Large vesicular nuclei with prominent nucleoli |
| Appears to have more aggressive behavior than usual carcinoma | Appears to have better behavior than usual carcinoma in some series |
Is Histiocytoid Carcinoma a variant of Lobular Carcinoma?
-
Most cases of histiocytoid carcinoma show linear and targetoid infiltration, are E cadherin negative and have at least focal intracytoplasmic lumens and many have adjacent LCIS
- These features suggest that at least in many cases, histiocytoid carcinoma could be considered a variant of lobular carcinoma
- A minority of cases have been reported that show infiltration more characteristic of ductal carcinoma and are E cadherin positve
